uu.seUppsala universitets publikationer
Ändra sökning
Avgränsa sökresultatet
123 1 - 50 av 115
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Akhter, Shahida
    et al.
    Univ Chittagong, Dept Phys, Chittagong 4331, Bangladesh..
    Hakim, M. A.
    BUET, Dept Glass & Ceram Engn, Dhaka, Bangladesh..
    Hoque, S. M.
    Atom Energy Ctr, Mat Sci Div, Dhaka 1000, Bangladesh..
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Glassy behavior of diluted Cu-Zn ferrites2018Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 452, s. 261-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic behavior of Zn substituted Cu-Zn spinel ferrites having chemical formula Cu1-xZnxFe2O4 (x = 0.7, 0.8, 0.9 and 1.0) has been studied by SQUID magnetometry, by means of magnetic hysteresis, field-cooled (FC) and zero-field-cooled (ZFC) magnetization, memory effect and low field ac susceptibility measurements. These measurements suggest that the ferrimagnetic phase of the x <= 0.8 samples is gradually turned into a spin glass (x >= 0.9). The compound with x = 0.9 exhibits the typical dynamical behavior of spin glasses, with indication of aging, rejuvenation and memory effects. The evolution of the magnetic properties of Cu-Zn spinel ferrites with substitution of Zn for Cu is discussed.

  • 2. Akhter, Shahida
    et al.
    Paul, D. P.
    Hoque, S. M.
    Hakim, M. A.
    Hudl, Matthias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Magnetic and magnetocaloric properties of Cu1-xZnxFe2O4 (x=0.6, 0.7, 0.8) ferrites2014Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 367, s. 75-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of Zn substitution on the magnetic and magnetocaloric properties of Cu1-xZnxFe2O4 (x=0.6, 0.7, 0.8) ferrites over a wide temperature range has been investigated. The polycrystalline samples were synthesized using the solid-state reaction at sintering temperature 1050 degrees C (1323 K) for 2 h and has been characterized by SQUID magnetometry. Magnetization versus temperature showed that all samples exhibit a paramagnetic to ferromagnetic transition with decreasing temperature. The Curie temperature T-c is found to decrease from 373 K for x=0.6 to 140 K for x=0.8 as well as the saturation magnetization Ms which shifts from 100 to 44 emu/gm. The magnetocaloric effect was obtained by measuring a family of M-I1 curves at set temperature intervals and calculating the entropy change, LIS for this system using the Maxwell relation. The AS of all samples increased with increasing applied field and showed a maximum around their respective 'Fe. The entropy change (Delta S) decreased with increasing Zn content, whereas the relative cooling power (RCP) slightly increased. The large RCP and Delta S found in Zn substitution Cu-Zn ferrites will be interesting for magnetic refrigeration near room temperature.

  • 3.
    Andersson, Mikael
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    De Toro, J. A.
    Lee, S. S.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Super spin dimensionality of a mono-dispersed and densely packed magnetic nanoparticle system2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The dynamics of a dense near mono-dispersed assembly of maghemite nanoparticles is investigated by measurements of the temperature dependence of the isothermal remnant magnetization induced by temporal application of weak magnetic fields at constant temperature. The results suggest that the dimensionality of the super spins of the particles is of Heisenberg character at high temperatures but crossover to become Ising like at lower temperatures.

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    Andersson, Mikael S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Pappas, Spyridon D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Stopfel, Henry
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Östman, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Stein, A.
    Brookhaven Natl Lab, Ctr Funct Nanomat, POB 5000, Upton, NY 11973 USA..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Kapaklis, Vassilios
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Thermally induced magnetic relaxation in square artificial spin ice2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 37097Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The properties of natural and artificial assemblies of interacting elements, ranging from Quarks to Galaxies, are at the heart of Physics. The collective response and dynamics of such assemblies are dictated by the intrinsic dynamical properties of the building blocks, the nature of their interactions and topological constraints. Here we report on the relaxation dynamics of the magnetization of artificial assemblies of mesoscopic spins. In our model nano-magnetic system - square artificial spin ice - we are able to control the geometrical arrangement and interaction strength between the magnetically interacting building blocks by means of nano-lithography. Using time resolved magnetometry we show that the relaxation process can be described using the Kohlrausch law and that the extracted temperature dependent relaxation times of the assemblies follow the Vogel-Fulcher law. The results provide insight into the relaxation dynamics of mesoscopic nano-magnetic model systems, with adjustable energy and time scales, and demonstrates that these can serve as an ideal playground for the studies of collective dynamics and relaxations.

    Ladda ner fulltext (pdf)
    fulltext
  • 5.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Angel De Toro, Jose
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Lee, Su Seong
    Inst Bioengn & Nanotechnol, 31 Biopolis Way, Singapore 138669, Singapore..
    Normile, Peter S.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Effects of the individual particle relaxation time on superspin glass dynamics2016Ingår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 5, artikel-id 054407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The low temperature dynamic magnetic properties of two dense magnetic nanoparticle assemblies with similar superspin glass transition temperatures T-g similar to 140 K are compared. The two samples are made from batches of 6 and 8 nm monodisperse gamma-Fe2O3 nanoparticles, respectively. The properties of the individual particles are extracted from measurements on reference samples where the particles have been covered with a thick silica coating. The blocking temperatures of these dilute assemblies are found at 12.5 K for the 6 nm particles and at 35 K for the 8 nm particles, which implies different anisotropy energy barriers of the individual particles and vastly different temperature evolution of their relaxation times. The results of the measurements on the concentrated particle assemblies suggest a strong influence of the particle energy barrier on the details of the aging dynamics, memory behavior, and apparent superspin dimensionality of the particles.

  • 6.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    De Toro, Jose Angel
    Lee, Su Seong
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ageing dynamics of a superspin glass2014Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 108, nr 1, s. 17004-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magnetization dynamics of a model superspin glass system consisting of nearly monodispersed close-packed maghemite particles of diameter 8 nm is investigated. The observed non-equilibrium features of the dynamics are qualitatively similar to those of atomic spin glass systems. The intrinsic relaxation function, as observed in zero-field-cooled magnetization relaxation experiments, depends on the time the sample has been kept at constant temperature (ageing). Accompanying low-field experiments show that the archetypal spin glass characteristics -ageing, memory and rejuvenation- are reproduced in this dense system of dipolar-dipolar interacting superspins.  

  • 7.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lee, Su Seong
    The Nanos, Inst Bioengn & Nanotechnol, Singapore 138669, Singapore..
    Normile, Peter S.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Singh, Gurvinder
    Norwegian Univ Sci & Technol, Dept Mat Sci & Engn, N-7491 Trondheim, Norway..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Angel De Toro, Jose
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Size-dependent surface effects in maghemite nanoparticles and its impact on interparticle interactions in dense assemblies2015Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 47, artikel-id 475703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The question of the dominant interparticle magnetic interaction type in random closely packed assemblies of different diameter (6.2-11.5 nm) bare maghemite nanoparticles (NPs) is addressed. Single-particle magnetic properties such as particle anisotropy and exchange bias field are first of all studied in dilute (reference) systems of these same NPs, where interparticle interactions are neglible. Substantial surface spin disorder is revealed in all particles except the smallest, viz. for diameters d = 8-11.5 nm but not for d = 6.2-6.3 nm. X-ray diffraction analysis points to a crystallographic origin of this effect. The study of closely packed assemblies of the d >= 8 nm particles observes collective (superspin) freezing that clearly appears to be governed by interparticle dipole interactions. However, the dense assemblies of the smallest particles exhibit freezing temperatures that are higher than expected from a simple (dipole) extrapolation of the corresponding temperatures found in the d >= 8 nm assemblies. It is suggested that the nature of the dominant interparticle interaction in these smaller particle assemblies is superexchange, whereby the lack of significant surface spin disorder allows this mechanism to become important at the level of interacting superspins.

  • 8.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Industriell teknik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Normile, Peter S.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Lee, Su Seong
    Inst Bioengn & Nanotechnol, 31 Biopolis Way, Singapore 138669, Singapore..
    Singh, Gurvinder
    Norwegian Univ Sci & Technol NTNU, Ugelstad Lab, Dept Mat Sci & Engn, Trondheim, Norway..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Angel De Toro, Jose
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Particle size-dependent superspin glass behavior in random compacts of monodisperse maghemite nanoparticles2016Ingår i: MATERIALS RESEARCH EXPRESS, ISSN 2053-1591, Vol. 3, nr 4, artikel-id 045015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dense random assemblies made from highly monodisperse gamma-Fe2O3 nanoparticles with sizes ranging from 6.2 to 11.5 nm have been investigated by DC and AC magnetometry. It is found that all assemblies undergo superspin glass phase transitions. The superspin glass phase transition temperature is strongly dependent on the particle size and the nature of the interparticle interaction. However the transition from superparamagnet to superspin glass, as evidenced by the shape of the ac-susceptibility curves and the dynamic critical exponents associated with the transition, is similar in all systems.

  • 9.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Normile, Peter S.
    Univ Castilla La Mancha, Spain.
    Lee, Su Seong
    Inst Bioengn & Nanotechnol, Singapore.
    Singh, Gurvinder
    Norwegian Univ Sci & Technol NTNU, Dept Mat Sci & Engn, Norway.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    De Toro, José A.
    Univ Castilla La Mancha, Spain.
    Magnetic properties of nanoparticle compacts with controlled broadening of the particle size distribution2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, nr 18, artikel-id 184431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Binary random compacts with different proportions of small (volume V) and large (volume 2V) essentially bare maghemite nanoparticles are used to investigate the effect of controllably broadening the particle size distribution on the magnetic properties of magnetic nanoparticle assemblies with strong dipolar interaction. A series of eight random mixtures of highly uniform 9.0- and 11.5-nm-diameter maghemite particles prepared by thermal decomposition is studied. In spite of the severely broadened size distributions in the mixed samples, well-defined superspin glass transition temperatures are observed across the series, their values increasing linearly with the weight fraction of large particles.

  • 10. Bandyopadhyay, Sulalit
    et al.
    Singh, Gurvinder
    Sandvig, Ioanna
    Sandvig, Axel
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kumar Puri, Anil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Glomm, Wilhelm Robert
    Synthesis and in vitro cellular interactions of superparamagnetic iron nanoparticles with a crystalline gold shell2014Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, s. 171-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fe@Au core-shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter similar to 24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV-vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications.

  • 11.
    Beran, P.
    et al.
    Nucl Phys Inst ACSR, Rez, Czech Republic..
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Moscow 105064, Russia..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Middey, S.
    Indian Assoc Cultivat Sci, Ctr Adv Mat, Kolkata 700032, India..
    Nag, A.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    Sarma, D. D.
    Indian Assoc Cultivat Sci, Ctr Adv Mat, Kolkata 700032, India.;Indian Inst Sci, Solid State & Struct Chem Unit, Bangalore 560012, Karnataka, India.;CSIR, NISE, New Delhi 110001, India..
    Ray, S.
    Indian Assoc Cultivat Sci, Ctr Adv Mat, Kolkata 700032, India.;Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Neutron powder diffraction study of Ba3ZnRu2-xIrxO9 (x=0, 1, 2) with 6H-type perovskite structure2015Ingår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 50, s. 58-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The triple perovskites Ba3ZnRu2-xIrxO9 with x = 0, 1, and 2 are insulating compounds in which Ru(Ir) cations form a dimer state. Polycrystalline samples of these materials were studied using neutron powder diffraction (NPD) at 10 and 295 K. No structural transition nor evidence of long range magnetic order was observed within the investigated temperature range. The results from structural refinements of the NPD data and its polyhedral analysis are presented, and discussed as a function of Ru/Ir content.

  • 12. Boschker, J. E.
    et al.
    Monsen, A. F.
    Nord, M.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Grepstad, J. K.
    Holmestad, R.
    Wahlstrom, E.
    Tybell, T.
    In-plane structural order of domain engineered La0.7Sr0.3MnO3 thin films2013Ingår i: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 93, nr 13, s. 1549-1562Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed structural study of tensile-strained La0.7Sr0.3MnO3 thin films. We use the substrate miscut to control the number of rhombohedral variants in the films and study the in-plane order and structural distortions. Using high-resolution X-ray diffraction, we demonstrate that step-edge induced lattice modulations occur in 4-variant films, whereas periodic twinning is the dominant in-plane order for 2-variant films. We show that the in-plane twinning angle is almost completely relaxed. However, the relaxation of shear strain by the out-of-plane twinning angle and the monoclinic distortion is only partial. Furthermore, the film thickness dependence of the domain width reveals that domain formation is a universal mechanism for shear strain relaxation. Finally, we show that the structural response to the transition from the paramagnetic to the ferromagnetic phase of La0.7Sr0.3MnO3 at 345K is smaller in 4-variant films compared to 2-variant films.

  • 13.
    Cedervall, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia;Uppsala Univ, Dept Engn Sci, Box 534, S-75121 Uppsala, Sweden.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. Uppsala Univ, Dept Chem, Angstrom Lab, Box 538, S-75121 Uppsala, Sweden.
    Beran, Premysl
    ESS, Tunavagen 24, S-22363 Lund, Sweden;Acad Sci Czech Republ, Nucl Phys Inst, Rez 25068, Czech Republic.
    Andersson, Mikael S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Faske, Tom
    Tech Univ Darmstadt, Inst Mat & Geowissensch, Alarich Weiss Str 2, D-64287 Darmstadt, Germany.
    Bazuev, Gennadii V.
    Russian Acad Sci, Inst Solid State Chem, Ural Branch, Ekaterinburg 620990, Russia.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    On the structural and magnetic properties of the double perovskite Nd2NiMnO62019Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 30, nr 17, s. 16571-16578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural, electronic and magnetic properties of phase pure and stoichiometric samples of the double perovskite Nd2NiMnO6. Photoectron spectroscopy revels a mixed valence of the transition metal sites where Ni has 3+/2+ oxidation states and Mn has 3+/4+. The compound orders ferromagnetically at 195 K. The magnetic structure was determined from the refinement of the neutron diffraction data. The results suggests that the B-site magnetic moments align along the crystallographic a-direction.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 14. Chao, K. S.
    et al.
    Huang, D. J.
    Okamoto, J.
    Lin, H.-J.
    Kaneko, Y.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Wu, W. B.
    Tokura, Y.
    Chen, C. T.
    Orbital Ordering of Manganites from Resonant Soft X-ray Scattering2007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 310, s. 819-Artikel i tidskrift (Refereegranskat)
  • 15. Chi, S.
    et al.
    Ye, F.
    Dai, P.
    Fernandez-Baca, J. A.
    Huang, Q.
    Lynn, J. W.
    Plummer, E. W.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kaneko, Y.
    Tokura, Y.
    Effect of antiferromagnetic spin correlations on lattice distortion and charge ordering in Pr0.5Ca1.5MnO42007Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 104, nr 10, s. 10796-Artikel i tidskrift (Refereegranskat)
  • 16. Choudhury, D.
    et al.
    Mandal, P.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Hazarika, A.
    Rajan, S.
    Sundaresan, A.
    Waghmare, U. V.
    Knut, Ronny
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Karis, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sarma, Dipankar Das
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Near-Room-Temperature Colossal Magnetodielectricity and Multiglass Properties in Partially Disordered La2NiMnO62012Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, nr 12, s. 127201-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report magnetic, dielectric, and magnetodielectric responses of the pure monoclinic bulk phase of partially disordered La2NiMnO6, exhibiting a spectrum of unusual properties and establish that this compound is an intrinsically multiglass system with a large magnetodielectric coupling (8%-20%) over a wide range of temperatures (150-300 K). Specifically, our results establish a unique way to obtain colossal magnetodielectricity, independent of any striction effects, by engineering the asymmetric hopping contribution to the dielectric constant via the tuning of the relative-spin orientations between neighboring magnetic ions in a transition-metal oxide system. We discuss the role of antisite (Ni-Mn) disorder in emergence of these unusual properties.

  • 17.
    Choudhury, Debraj
    et al.
    Solid State and Structural Chemistry Unit, and Department of Physics, at Indian Institute of Science, Bangalore, Indien.
    Mukherjee, S
    Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Indien.
    Mandal, P
    Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Sundaresan, A
    Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Waghamare, U V
    Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Bhattacharjee, Satadeep
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lazor, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Sanyal, Biplab
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sharma, Ajay
    Department of Physics, Indian Institute of Science, Bangalore, Indien.
    Bhat, S V
    Department of Physics, Indian Institute of Science, Bangalore, Indien.
    Karis, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Sarma, Dipankar Das
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Tuning of dielectric properties and magnetism of SrTiO3 by site-specific doping of Mn2011Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 12, s. 125124-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Combining experiments with first-principles calculations, we show that site-specific doping of Mn into SrTiO(3) has a decisive influence on the dielectric properties of these doped systems. We find that phonon contributions to the dielectric constant invariably decrease sharply on doping at any site. However, a sizable, random dipolar contribution only for Mn at the Sr site arises from a strong off-centric displacement of Mn in spite of Mn being in a non-d(0) state; this leads to a large dielectric constant at higher temperatures and gives rise to a relaxor ferroelectric behavior at lower temperatures. We also investigate magnetic properties in detail and critically reevaluate the possibility of a true multiglass state in such systems.

  • 18. De Toro, J. A.
    et al.
    Lee, S. S.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Normile, P. S.
    Salazar, D.
    Cheong, J. L.
    Muñiz, P.
    Riveiro, J. M.
    Hillenkamp, M.
    Tamion, A.
    Tournus, F.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ideal superspin glass behaviour in a random-close-packed ensemble of maghemite nanoparticles2014Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 521, nr 1, s. 012011-Artikel i tidskrift (Refereegranskat)
  • 19.
    De Toro, José A.
    et al.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain.
    Vasilakaki, Marianna
    NCSR Demokritos, Inst Nanosci & Nanotechnol, Athens 15310, Greece.
    Lee, Su Seong
    Inst Bioengn & Nanotechnol, 31 Biopolis Way, Singapore 138669, Singapore.
    Andersson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Normile, Peter S.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain.
    Yaacoub, Nader
    Univ Maine, CNRS, UMR 6283, Inst Mol & Mat Mans, F-72085 Le Mans, France.
    Murray, Peyton
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA.
    Sanchez, Elena H.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain.
    Muñiz, Pablo
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain.
    Peddis, Davide
    CNR, Ist Struttura Mat, I-00015 Monterotondo Scale, RM, Italy.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Liu, Kai
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA.
    Geshev, Julian
    Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil.
    Trohidou, Kalliopi N.
    NCSR Demokritos, Inst Nanosci & Nanotechnol, Athens 15310, Greece.
    Nogués, Josep
    CSIC, Catalan Inst Nanosci & Nanotechnol ICN2, Campus UAB, Barcelona 08193, Spain.;Barcelona Inst Sci & Technol, Campus UAB, Barcelona 08193, Spain.;ICREA, Pg Lluis Co 23, Barcelona 08010, Spai.
    Remanence Plots as a Probe of Spin Disorder in Magnetic Nanoparticles2017Ingår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, nr 19, s. 8258-8268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Remanence magnetization plots (e.g., Henkel or delta M plots) have been extensively used as a straightforward way to determine the presence and intensity of dipolar and exchange interactions in assemblies of magnetic nanoparticles or single domain grains. Their evaluation is particularly important in functional materials whose performance is strongly affected by the intensity of interparticle interactions, such as patterned recording media and nanostructured permanent magnets, as well as in applications such as hyperthermia and magnetic resonance imaging. Here, we demonstrate that delta M plots may be misleading when the nanoparticles do not have a homogeneous internal magnetic configuration. Substantial dips in the delta M plots of gamma-Fe2O3 nanoparticles isolated by thick SiO2 shells indicate the presence of demagnetizing interactions, usually identified as dipolar interactions. results, however, demonstrate that it is the inhomogeneous spin structure of the nanoparticles, as most clearly evidenced by Mossbauer measurements, that has a pronounced effect on the delta M plots, leading to features remarkably similar to those produced by dipolar interactions. X-ray diffraction results combined with magnetic characterization indicate that this inhomogeneity is due to the presence of surface structural (and spin) disorder. Monte Carlo simulations unambiguously corroborate the critical role of the internal magnetic structure in the delta M plots. Our findings constitute a cautionary tale on the widespread use of remanence plots to assess interparticle interactions as well as offer new perspectives in the use of Henkel and delta M plots to quantify the rather elusive inhomogeneous magnetization states in nanoparticles.

  • 20. Hossain, M. A.
    et al.
    Hu, Z.
    Haverkort, M. W.
    Burnus, T.
    Chang, C. F.
    Klein, S.
    Denlinger, J. D.
    Lin, H.-J.
    Chen, C. T.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kaneko, Y.
    Tokura, Y.
    Satow, S.
    Yoshida, Y.
    Takagi, H.
    Tanaka, A.
    Elfimov, I. S.
    Sawatzky, G. A.
    Tjeng, L. H.
    Damascelli, A.
    Crystal-field level inversion in lightly Mn-doped Sr3Ru2O72008Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 1, s. 016404-Artikel i tidskrift (Refereegranskat)
  • 21. Hossain, M. A.
    et al.
    Zegkinoglou, I.
    Chuang, Y.-D.
    Geck, J.
    Bohnenbuck, B.
    Cruz Gonzalez, A. G.
    Wu, H.-H.
    Schüßler-Langeheine, C.
    Hawthorn, D. G.
    Denlinger, J. D.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tokura, Y.
    Satow, S.
    Takagi, H.
    Hussain, Z.
    Keimer, B.
    Sawatzky, G. A.
    Damascelli, A.
    Electronic superlattice revealed by resonant scattering from random impurities in Sr3Ru2O72013Ingår i: Bioscience Reports, ISSN 0144-8463, E-ISSN 1573-4935, Vol. 3, s. 2299-Artikel i tidskrift (Refereegranskat)
  • 22. Hossain, M
    et al.
    Bohnebuck, B
    Chuang, Y D
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Magnetic Superstructure and Metal-Insulator Transition in Mn-Substituted Sr3Ru2O72009Ingår i: Condensed Matter Physics, ISSN 1607-324X, E-ISSN 2224-9079, Vol. 0906Artikel i tidskrift (Refereegranskat)
  • 23.
    Hudl, Matthias
    et al.
    KTH Royal Inst Technol, ICT Mat Phys, Electrum 229, SE-16440 Kista, Sweden..
    Lazor, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gavriliuk, Alexander G
    ETH, Dept Mat, CH-8093 Zurich, Switzerland; Russian Acad Sci, Inst Nucl Res, Moscow 117312, Russia.
    Struzhkin, Viktor
    Carnegie Inst Sci, Geophys Lab, Washington, DC 20015 USA.
    PPMS-based set-up for Raman and luminescence spectroscopy at high magnetic field, high pressure and low temperature2015Ingår i: EPJ Techniques and Instrumentation, ISSN 2195-7045, Vol. 2, nr 1, artikel-id 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an experimental set-up permitting Raman and luminescence spectroscopy studies in a commercial Physical Properties Measurement System (PPMS) from Quantum Design. Using this experimental set-up, gaseous, liquid and solid materials, in bulk or thin film form, may be investigated. The set-up is particularly suitable for the study of the spin-lattice coupling in strongly correlated oxide materials utilizing several different stimuli, e.g. magnetic and electric fields, high pressure and low temperatures. Details for the Raman extension, sample holder assembly and optical design, as well as data acquisition and measurement routine are described. Finally, we present exemplary results collected using the set-up, measured on reference materials, as well as on a correlated transition metal oxide.

    Ladda ner fulltext (pdf)
    fulltext
  • 24.
    Hudl, Matthias
    et al.
    Stockholm Univ, Dept Phys, Chem Phys, SE-10691 Stockholm, Sweden..
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tunable exchange bias in dilute magnetic alloys: chiral spin glasses2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 19964Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A unidirectional anisotropy appears in field cooled samples of dilute magnetic alloys at temperatures well below the cusp temperature of the zero field cooled magnetization curve. Magnetization measurements on a Cu(13.5 at% Mn) sample show that this anisotropy is essentially temperature independent and acts on a temperature dependent excess magnetization, Delta M. The anisotropy can be partially or fully transferred from being locked to the direction of the cooling field at lower fields to becoming locked to the direction of Delta M at larger fields, thus instead appearing as a uniaxial anisotropy. This introduces a deceiving division of the anisotropy into a superposition of a unidirectional and a uniaxial part. This two faced nature of the anisotropy has been empirically scrutinized and concluded to originate from one and the same exchange mechanism: the Dzyaloshinsky-Moriya interaction.

  • 25.
    Hudl, Matthias
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ivanov, Sergey
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Bazuev, G.V.
    nstitute of Solid-State Chemistry, Ural Branch of the Russian Academy of Science, Ekaterinburg, Russia.
    Lazor, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Investigation of the magnetic phase transition and magnetocaloric properties of the Mn2FeSbO6 ilmenite2013Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 331, s. 193-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic phase transition and magnetocaloric properties of both mineral and synthetic melanostibite Mn2FeSbO6 with ilmenite-type structure have been studied. Mn2FeSbO6 orders ferrimagnetically below 270 K and is found to undergo a second-order magnetic phase transition. The associated magnetic entropy change was found to be 1.7 J/kg K for the mineral and 1.8 J/kg K for the synthetic melanostibite for 5 T field change. For the synthetic Mn2FeSbO6 the adiabatic temperature change was estimated from magnetic- and specific heat measurements and amounts to 0.2 K in 1 T field change. Perspectives of the functional properties of Mn2FeSbO6-based materials are discussed.

  • 26.
    Hudl, Mattias
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Weil, M
    Institute for Chemical Technologies and Analytics, Vienna Unviersity of Technology, Vienna, Österrike.
    Carolus, V
    HISKP, Universität Bonn, Tyskland.
    Lottermoser, Th
    HISKP, Universität Bonn, Tyskland, och Department of Materials, ETH Zürich, Schweiz.
    Fiebig, M
    HISKP, Universität Bonn, Tyskland, och Department of Materials, ETH Zürich, Schweiz.
    Tokunaga, Y
    Multiferroics Project, ERATO, Japan Science and Technology Agency (JST), Wako, Japan.
    Taguchi, Y
    Cross-Correlated materials Research Group (CMRG) and Correlated Electron Research Group (CERG), ASI, RIKEN, Wako, Japan.
    Tokura, Y
    Multiferroics Project, ERATO, Japan Science and Technology Agency (JST), Cross-Correlated materials Research Group (CMRG) and Correlated Electron Research Group (CERG), ASI, RIKEN,Wako, Dept of Applied Physics, University of Tokyo,Japan.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Complex magnetism and magnetic-field-driven electrical polarization of Co(3)TeO(6)2011Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 18, s. 180404-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic and electrical properties of Co(3)TeO(6) single crystals with corundum-related structure reveal a magnetic-field-induced polarization below 21 K. A sharp peak in the specific heat at approximate to 18 K indicates a reconstructive-type first-order phase transition. From second-harmonic generation measurements, breaking of inversion symmetry is evident and the point-group symmetry was determined as m. The temperature and magnetic-field dependences of the magnetic and electrical polarizations are discussed in the light of the SHG results.

  • 27. Ivanov, S. A.
    et al.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Ritter, C.
    Neutron diffraction studies and the magnetism of an ordered perovskite: Ba2CoTeO62010Ingår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, nr 23, s. 5490-5499Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex perovskite Ba2CoTeO6 (BCTO) has been synthesised, and the crystal structure and magnetic properties have been investigated using a combination of X-ray and neutron powder diffraction, electron microscopy and dielectric, calorimetric and magnetic measurements. It is shown that at room temperature this compound adopts the 6L-trigonal perovskite structure, space group P (3) over barm (s.g. 164) (a = 5.7996(1) angstrom, c = 14.2658(3) angstrom). The structure comprises dimers of face-sharing octahedra as well as octahedra which share only vertices with their neighbours. Dielectric measurements indicate a diffuse transition of antiferroelectric nature near 280 K. A long-range antiferromagnetically ordered state has been identified from neutron diffraction and magnetic studies. The magnetic diffraction peaks were registered below the magnetic transition at about 15 K and a possible model for the magnetic structure is proposed. The structural and magnetic features of this compound are discussed and compared with those of other Co-based quaternary oxides adopting the perovskite structure.

  • 28. Ivanov, S. A.
    et al.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Ritter, C.
    Structural and magnetic properties of the ordered perovskite Pb2CoTeO62010Ingår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, nr 46, s. 11136-11148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex perovskite Pb2CoTeO6 (PCTO) has been prepared as polycrystalline powders by a solid state reaction route, and the crystal structure and magnetic properties have been investigated using a combination of X-ray and neutron powder diffraction, electron microscopy, dielectric, calorimetric and magnetic measurements. It was shown that at room temperature this compound adopts a trigonal perovskite structure, space group R (3) over bar (a = 5.6782(1) angstrom, c = 13.8552(3) angstrom). The compound undergoes a number of temperature-induced phase transitions and adopts four different structures in the temperature range 5 500 K: monoclinic in P2(1)/n (5 < T < 125 K, tilt system (a(+)b(-)b(-))), monoclinic in I2/m (125 < T < 210 K, tilt system (a(0)b(-)b(-))), rhombohedral in R (3) over bar (210 < T < 370 K, tilt system (a(-)a(-)a(-))), and finally cubic in Fm (3) over barm (above 370 K without any tilting). These structural phase transitions are coupled to changes in the dielectric constant and the heat capacity around 210 and 370 K. A long-range antiferromagnetically ordered state has been identified from neutron powder diffraction and magnetic studies at different temperatures. Magnetic diffraction peaks were registered below the transition at about 16 K and a possible model for the magnetic structure is proposed. Possible coexistence of long-range ordering of the electrical dipoles and the magnetic moments at low temperatures making PCTO a potential multiferroic candidate is discussed.

  • 29.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Beran, P.
    Bazuev, G. V.
    Ericsson, T.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kumar, P. Anil
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Crystal structure and antiferromagnetic spin ordering of LnFe(2/3)Mo(1/3)O(3) (Ln = Nd, Pr, Ce, La) perovskites2015Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, nr 9, artikel-id 094418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stoichiometric polycrystalline samples of LnFe(2/3)Mo(1/3)O(3) (Ln = Nd, Pr, Ce, La) have been prepared by solid-state reaction and studied by means of x-ray and neutron powder diffraction as well as Mossbauer spectroscopy and magnetic measurements. All samples were found to be of single phase and to have Pnma symmetry with valence state +3 of Fe and Mo. It is demonstrated that the B-site cations of LnFe(2/3)Mo(1/3)O(3) in accord with LnFeO(3) order in a G-type antiferromagnetic structure with the magnetic moments aligned along the b axis. However, with significantly lower Neel temperatures than their LnFeO(3) parent compounds. The Fe-O-Fe bond lengths and bond angles and thus themagnitude of the antiferromagnetic superexchange interaction are found to systematically change with the ionic radius of Ln such that T-N increases with increasing radius. Only the CeFe2/3Mo1/3O3 compound experiences a low temperature spin reorientation from alignment along the b axis to the a axis.

  • 30.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Center of Materials Science, Karpov Institute of Physical Chemistry, Moscow, Russia..
    Bush, A. A.
    Moscow Technol Univ, Moscow 119434, Russia..
    Hudl, M.
    Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden..
    Stash, A. I.
    Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia..
    Andre, G.
    CEA, Lab Leon Brillouin, Saclay, France..
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Cherepanov, V. M.
    Kurchatov Inst, Natl Res Ctr, Moscow 123182, Russia..
    Stepanov, A. V.
    Moscow Technol Univ, Moscow 119434, Russia..
    Kamentsev, K. E.
    Moscow Technol Univ, Moscow 119434, Russia..
    Tokunaga, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan..
    Taguchi, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan..
    Tokura, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan.;Univ Tokyo, Dept Appl Phys, Tokyo 1138656, Japan..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Spin and dipole order in geometrically frustrated mixed-valence manganite Pb3Mn7O152016Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 27, nr 12, s. 12562-12573Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural, magnetic, and dielectric properties of Pb3Mn7O15 have been investigated using high-quality single crystals. Pb3Mn7O15 adopts a pseudo-hexagonal orthorhombic structure, with partially filled Kagom, layers connected by ribbons of edge-sharing MnO6 octahedra and intercalated Pb cations. There are 9 inequivalent sites in the structure for the Mn ions, which exist both as Mn3+ and Mn4+. Pb3Mn7O15 undergoes an antiferromagnetic transition below T-N similar to 67 K, with significant geometric frustration. Neutron powder diffraction on crushed single crystals allowed us to determine the low-temperature antiferromagnetic magnetic structure. We discuss the magnetic interaction pathways in the structure and possible interplay between the structural distortions imprinted by the lone-electron pair of Pb2+ cations and Mn3+/Mn4+ charge ordering.

    Ladda ner fulltext (pdf)
    fulltext
  • 31.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia..
    Bush, A. A.
    Moscow State Univ Informat Technol RadioEngn & El, Pr Ventadskogo 78, Moscow 119454, Russia..
    Ritter, C.
    Inst Laue Langevin, BP 156, F-38042 Grenoble, France..
    Behtin, M. A.
    Moscow State Univ Informat Technol RadioEngn & El, Pr Ventadskogo 78, Moscow 119454, Russia..
    Cherepanov, V. M.
    Kurchatov Inst, Natl Res Ctr, Pl Kurchatova 1, Moscow 123182, Russia..
    Autieri, Carmine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Kvashnin, Yaroslav O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Di Marco, Igor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Sanyal, Biplab
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Kumar, P. Anil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Evolution of the structural and multiferroic properties of PbFe2/3W1/3O3 ceramics upon Mn-doping2017Ingår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 187, s. 218-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The perovskite system Pb(Fe1-xMnx)(2/3)W1/3O3 (0 <= x <= 1, PFMWO) has been prepared by conventional solid-state reaction under different sintering conditions. Structures and phase composition as well as thermal, magnetic and dielectric properties of the compounds have been systematically investigated experimentally and by first-principles density functional calculations. A clean perovskite phase is established at room temperature for compositions 0 <= x <= 0.4. Rietveld refinements of X-ray and neutron powder diffraction patterns demonstrate that the compounds crystallize in space group Pm-3m (0 <= x <= 0.4). The degree of ordering of the Fe and W/Mn cations was found to depend on the concentration of Mn. First-principles calculations suggest that the structural properties of PFMWO are strongly influenced by the Jahn Teller effect. The PFMWO compounds behave as relaxor ferroelectrics at weak Mn-doping with a dielectric constant that rapidly decreases with increasing Mn content. A low temperature antiferromagnetic G-type order with propagation vector k = (1/2,1/2,1/2) is derived from neutron powder diffraction data for the samples with x <= 0.4. However with increasing doping concentration, the magnetic order is perturbed. First principles calculations show that the dominant exchange coupling is antiferromagnetic and occurs between nearest neighbor Fe atoms. When the system is doped with Mn, a relatively weak ferromagnetic (FM) interaction between Fe and Mn atoms emerges. However, due to the presence of this FM interaction, the correlation length of the magnetic order is greatly shortened already at rather low doping levels.

  • 32.
    Ivanov, Sergey A
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10,K-64, Moscow 105064, Russia.
    Bush, Alexander A
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Stash, Adam I
    Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10,K-64, Moscow 105064, Russia.
    Kamentsev, Konstantin E
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Shkuratov, Valerii Ya
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Kvashnin, Yaroslav O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Autieri, Carmine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Di Marco, Igor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Sanyal, Biplab
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Polar Order and Frustrated Antiferromagnetism in Perovskite Pb2MnWO6 Single Crystals.2016Ingår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, nr 6, s. 2791-2805Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single crystals of the multiferroic double-perovskite Pb2MnWO6 have been synthesized and their structural, thermal, magnetic and dielectric properties studied in detail. Pure perovskite-phase formation and stoichiometric chemical composition of the as-grown crystals are confirmed by X-ray single-crystal and powder diffraction techniques as well as energy-dispersive X-ray and inductively coupled plasma mass spectrometry. Detailed structural analyses reveal that the crystals experience a structural phase transition from the cubic space group (s.g.) Fm3̅m to an orthorhombic structure in s.g. Pn21a at about 460 K. Dielectric data suggest that a ferrielectric phase transition takes place at that same temperature, in contrast to earlier results on polycrystalline samples, which reported a transition to s.g. Pnma and an antiferroelectric low-temperature phase. Magnetic susceptibility measurements indicate that a frustrated antiferromagnetic phase emerges below 8 K. Density functional theory based calculations confirm that the cationic order between Mn and W is favorable. The lowest total energy was found for an antiferromagnetically ordered state. However, analyses of the calculated exchange parameters revealed strongly competing antiferromagnetic interactions. The large distance between the magnetic atoms, together with magnetic frustration, is shown to be the main reason for the low value of the ordering temperature observed experimentally. We discuss the structure-property relationships in Pb2MnWO6 and compare these observations to reported results on related Pb2BWO6 perovskites with different B cations.

  • 33.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kumar Puri, Anil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bush, A. A.
    Ottosson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Temperature evolution of structural and magnetic properties of stoichiometric LiCu2O2: Correlation of thermal expansion coefficient and magnetic order2014Ingår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 34, s. 97-101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Temperature-dependent crystallographic and magnetic studies on stoichiometric single crystals of LiCu2O2 are reported. The temperature dependence of the lattice parameters was extracted from X-ray powder diffractograms collected on crushed single crystals, from 12 K to 295 K. The magnetic properties are similar to earlier findings demonstrating antiferromagnetic ordering below 25 K. Evidence of magnetoelastic coupling is observed in the thermal expansion along the c-direction; not only at the low temperature antiferromagnetic transitions, but an anomalous behavior of the thermal expansion indicate magnetoelastic coupling also to the magnetic ordering related to a weak spontaneous magnetic moment appearing at 150 K. Ac-susceptibility measurements at different frequencies and superposed dc-fields are employed to further characterize this magnetic anomaly.

  • 34.
    Ivanov, Sergey A
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Politova, E
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ritter, C
    Institute Laue Langevin, Grenoble Frankrike.
    Proidakova, V
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Structural and magnetic properties of Mn3-xCdxTeO6 (x = 0, 1, 1.5 and 2)2012Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 324, nr 8, s. 1637-1644Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mn(3)TeO(6) exhibits a corundum-related A(3)TeO(6) structure and a complex magnetic structure involving two magnetic orbits for the Mn atoms [Ivanov et al., 2011 [3]]. Mn(3-x)Cd(x)TeO(6) (x = 0, 1, 1.5, and 2) ceramics were synthesized by solid state reaction and investigated using X-ray powder diffraction, electron microscopy, and calorimetric and magnetic measurements. Cd(2+) replaces Mn(2+) cations without greatly affecting the structure of the compound. The Mn and Cd cations were found to be randomly distributed over the A-site. Magnetization measurements indicated that the samples order antiferromagnetically at low temperature with a transition temperature that decreases with increasing Cd doping. The nuclear and magnetic structure of one specially prepared (114)Cd containing sample: Mn(1.5) (114)Cd(1.5)TeO(6), was studied using neutron powder diffraction over the temperature range 2-295 K. Mn(1.5) (114)Cd(1.5)TeO(6) was found to order in an incommensurate helical magnetic structure, very similar to that of Mn(3)TeO(6) [Ivanov et al., 2011 [3]]. However, with a lower transition temperature and the extension of the ordered structure confined to order 240(10) angstrom.

  • 35.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ritter, C.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Golubko, N
    Mosunov, A
    Politova, E D
    Weil, M
    Chemical pressure effects on structural, dielectric and magnetic properties of solid solutions Mn3-xCoxTeO62014Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 50, s. 42-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of Co2+ doping on the structural, magnetic and dielectric properties of the multiferroic frustrated antiferromagnet Mn3TeO6 have been investigated. Ceramic samples of the solid solution series Mn3-xCoxTeO6 were prepared by a solid-state reaction route. X-ray and neutron powder diffraction and electron microscopy techniques were combined with calorimetric, dielectric and magnetic measurements to investigate the dependence of the crystal structure and physical properties on temperature and composition. It is shown that the compounds with x <= 2.4 adopt the trigonal corundum-related structure of pure Mn3TeO6 (space group 18) in the temperature range 5-295 K and that the lattice parameters a and c and the unit-cell volume V decrease linearly with increasing Co2+ concentration. The low-temperature magnetic susceptibility and heat capacity data evidence the antiferromagnetic ordering of all samples. The Neel temperature linearly increases with Co2+ concentration x. Curie-Weiss fits of the high temperature susceptibility indicate that the magnetic frustration decreases with x. The derived magnetic structure of Mn3TeO6 can be described as an incommensurately modulated magnetic spin state with k = [0, 0, k(z)] and an elliptical spin-spiral order of spins within the chains of MnO6 octahedra. With increasing Co2+ concentration the propagation vector kz changes from 0.453 (x = 0) to 0.516 (x = 2.4). The magnetic anisotropy changes as well, leading to a reorientation of the spiral-basal plane. A possible coexistence of long-range order of electrical dipoles and magnetic moments in Mn3-xCoxTeO6 is discussed.

  • 36.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ritter, C.
    Politova, E.
    Kaleva, G.
    Mosunov, A.
    Stefanovich, S.
    Weil, M.
    Spin and Dipole Ordering in Ni2InSbO6 and Ni2ScSbO6 with Corundum-Related Structure2013Ingår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 25, nr 6, s. 935-945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex metal oxides Ni2InSbO6 (NISO) and Ni2ScSbO6 (NSSO) have been prepared in the form of polycrystalline powders by a solid state reaction route. The crystal structure and magnetic properties of the compounds were investigated using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements. The compounds adopt a trigonal structure, space group R3, of the corundum related Ni3TeO6 (NTO) type. Only one of the octahedral Ni positions (Ni(2)) of the NTO structure was found to be occupied by In (Sc). NTO has noncentrosymmetric structure and is ferroelectric below 1000 K; dielectric and second harmonic measurements suggest that also NISO and NSSO are correspondingly ferroelectric. Magnetization measurements signified antiferromagnetic ordering below T-N = 60 K (NSSO) and 76 K (NISO). The magnetic structure is formed by two antiferromagnetically coupled incommensurate helices with the spiral axis along the b-axis and propagation vector k = [0, k(y),0] with k(y) = 0.036(1) (NSSO) and k(y) = 0.029(1) (NISO). The observed structural and magnetic properties of NISO and NSSO are discussed and compared with those of NTO.

  • 37.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Ritter, C
    Instittue Laue Langevin, Grenoble, Frankrike.
    Golubko, N V
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Politova, E D
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Weil, M
    Institute for Chemical Tecnologies and Analytics, Vienna University of Technology, Vienna, Österrike.
    New type of incommensurate magnetic ordering in Mn(3)TeO(6)2011Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 46, nr 11, s. 1870-1877Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex metal oxide Mn(3)TeO(6) exhibits a corundum related structure and has been prepared both in forms of single crystals by chemical transport reactions and of polycrystalline powders by a solid state reaction route. The crystal structure and magnetic properties have been investigated using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric and magnetic measurements. At room temperature this compound adopts a trigonal structure, space group R (3) over bar with a = 8.8679(1) angstrom. c = 10.6727(2) angstrom. A long-range magnetically ordered state is identified below 23 K. An unexpected feature of this magnetic structure is several types of Mn-chains. Under the action of the incommensurate magnetic propagation vector k = [0, 0, 0.4302(1)] the unique Mn site is split into two magnetically different orbits. One orbit forms a perfect helix with the spiral axis along the c-axis while the other orbit has a sine wave character along the c-axis.

  • 38.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Moscow 105064, Russia..
    Ritter, C.
    Inst Laue Langevin, BP 156, F-38042 Grenoble, France..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Weil, M.
    Vienna Univ Technol, Inst Chem Technol & Analyt, A-1060 Vienna, Austria..
    Carolus, V.
    Univ Bonn, HISKP, Nussallee 14-16, D-53115 Bonn, Germany..
    Lottermoser, Th
    ETH, Dept Mat, Vladimir Prelog Weg 4, CH-8093 Zurich, Switzerland..
    Fiebig, M.
    ETH, Dept Mat, Vladimir Prelog Weg 4, CH-8093 Zurich, Switzerland..
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    New insights into the multiferroic properties of Mn3TeO62017Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, nr 8, artikel-id 085001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mn3TeO6 has a trigonal corundum related structure (space group R (3) over bar), and orders in an incommensurate antiferromagnetic (AFM) structure at T-N approximate to 24 K. A weak ferroelectric order below T* similar to 21 K has recently been reported. In order to investigate possible structural changes below T-N leading to the observed dipole order, we have performed a detailed study of the crystal and magnetic structures of Mn3TeO6 using neutron powder diffraction (NPD) in the temperature range of 5-40 K. Complementary low-temperature second harmonic generation (SHG) measurements were performed in order to confirm the reported dipole order at T*. No change in the rhombohedral symmetry associated with a possible displacive phase transition at T* was observed in the long-range structural correlations, and it appears that Mn3TeO6 keeps the same incommensurately modulated magnetic spin structure with the propagation vector k = (0; 0; 0.43) in the whole temperature range from 5 to 24 K.

  • 39.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sahu, J. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Voronkova, V. I.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Structure and magnetism in hexagonal tungsten bronze metal oxides AM(1/3)W(8/3)O(9) (A-K, Rb, Cs; M-Cr, Fe)2015Ingår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 40, s. 44-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure and magnetic properties of hexagonal tungsten bronzes AM(1/3)W(8/3)O(9) (A-K+, Rb+, Cs+; M- Cr3+, Fe3+) have been investigated. Pure ceramic samples were synthesized by solid-state reaction. The samples have been studied by X-ray powder diffraction in combination with magnetic measurements. The compounds crystallize in hexagonal space group P6(3)/mcm. The substitution of magnetic ions into the WO6 octahedra yields dilute antiferromagnetic Cr3+-O2--Cr3+(or Fe3+-O2--Fe3+) superexchange interaction causing the appearance of short-range magnetic order at low temperatures. The antiferromagnetic character of the interaction is supported by negative values of the derived Curie-Weiss temperatures, qCW. The magnitude of qCW is found to decrease with increasing ionic radius of the A cation. 

  • 40.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ul Vorontsovo Pole,10, Moscow 105064, Russia..
    Sarkar, Tapati
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fortalnova, Elena A.
    RUDN Univ, Ul Miklukho Maklaya 6, Moscow 117198, Russia..
    Politova, Ekaterina D.
    Karpov Inst Phys Chem, Ul Vorontsovo Pole,10, Moscow 105064, Russia..
    Stefanovich, Sergey Yu.
    Karpov Inst Phys Chem, Ul Vorontsovo Pole,10, Moscow 105064, Russia..
    Safronenko, Marina G.
    RUDN Univ, Ul Miklukho Maklaya 6, Moscow 117198, Russia..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Composition dependence of the multifunctional properties of Nd-doped Bi4Ti3O12 ceramics2017Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 28, nr 11, s. 7692-7707Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sample preparation, evolution of the crystal structure with Nd content at room temperature, as well as dielectric and magnetic properties of polycrystalline Bi4-xNdxTi3O12 solid solutions (x = 0.0, 0.5, 1.0, 1.5, and 2.0) are reported. These solid solutions were structurally characterized by X-ray powder diffraction using Rietveld refinements. For x <= 1.0, the samples crystallize in an orthorhombic symmetry. The structural data could be refined using the polar orthorhombic space group B2cb. The orthorhombicity decreases with increasing Nd3+ concentration, and a paraelectric tetragonal structure (space group I4/mmm) is stabilized for x > 1. The ferroelectric Curie temperature was found to monotonously decrease with increasing Nd concentration. A polar-to-nonpolar phase transition takes place near x = 1, reflecting the existence of a morphotropic phase boundary between 1.0 < x < 1.5 at room temperature. All samples were found to be paramagnetic down to 5 K, however, the presence of significant antiferromagnetic interaction is inferred from Curie-Weiss analyses of the temperature dependence of the magnetic susceptibility of the doped samples. The effect of Nd3+ substitution on structure-property relationship is discussed and compared to that of other lanthanide cations.

    Ladda ner fulltext (pdf)
    fulltext
  • 41.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Porcher, F.
    Andre, G.
    Ericsson, T.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sadovskaya, N.
    Kaleva, G.
    Politova, E.
    Baldini, M.
    Sun, C.
    Arvanitis, Dimitri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik V. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Kumar, P. Anil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Structural and magnetic properties of nickel antimony ferrospinels2015Ingår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 158, s. 127-137Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spinel-type compounds of Fe-Ni-Sb-O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mossbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd - 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mossbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe0.8Ni1.8Sb0.4O4 was determined, with Sb5+ cations occupying octahedral sites, and Fe3+ and Ni2+ occupying both tetrahedral and octahedral sites. Fe3+ mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni2+ mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point.

  • 42.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Porcher, F.
    Ericsson, Tore
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Mosunov, A.
    Beran, P.
    Korchaginaa, S.K.
    Anil Kumar, Puri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Preparation, structural, dielectric and magnetic properties of LaFeO3-PbTiO3 solid solutions2012Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, nr 11, s. 3253-3268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid solutions of (1−x)LaFeO3–(x)PbTiO3 (0 < x < 1) have been prepared by conventional solid-state reaction. These complex perovskites have been studied by means of X-ray (XRPD) and neutron powder (NPD) diffraction, complemented with dielectric, magnetic, heat capacity and Mössbauer measurements. Complete solubility in the perovskite series was demonstrated. The NPD and XRPD patterns were successfully refined as orthorhombic (x ≤ 0.7) and tetragonal (x ≥ 0.8). A composition-driven phase transformation occurs within the interval 0.7 < x < 0.8. The samples with x < 0.5 showed evidence of long-range magnetic ordering with an G-type antiferromagnetic arrangement of the magnetic moments of the Fe3+ cations in the B-site with propagation vector k = (0,0,0). Based on the obtained experimental data, a combined structural and magnetic phase diagram has been constructed. The factors governing the structural, dielectric and magnetic properties of (1−x)LaFeO3–(x)PbTiO3 solid solutions are discussed, as well as their possible multiferroicity.

  • 43.
    Ivanov, Sergey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ritter, C.
    Institute Laue Langevin, Grenoble, Frankrike.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Andre, G.
    Laboratoire Leon Brillouin, CEA, Saclay, Frankrike.
    Golubko, N. V.
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Politova, E. D.
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Weil, M.
    Institute for Chemical Technologies and Analytics, Vienna University of Technology, Wien, Österrike.
    Temperature-dependent multi-k magnetic structure in multiferroic Co3TeO62012Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, nr 1, s. 63-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A complex magnetic order of the multiferroic compound Co(3)TeO(6) has been revealed by neutron powder diffraction studies on ceramics and crushed single crystals. The compound adopts a monoclinic structure (s.g. C2/c) in the studied temperature range 2-300 K but exhibits successive antiferromagnetic transitions at low temperature. Incommensurate antiferromagnetic order with the propagation vector k(1) = (0, 0.485, 0.055) sets in at 26 K. A transition to a second antiferromagnetic structure with k(2) = (0, 0, 0) takes place at 21.1 K. Moreover, a transition to a commensurate antiferromagnetic structure with k(3) = (0, 0.5, 0.25) occurs at 17.4 K. The magnetic structures have been determined by neutron powder diffraction using group theory analysis as a preliminary tool. Different coordinations of the Co(2+) ions involved in the low-symmetry C2/c structure of Co(3)TeO(6) render the exchange-interaction network very complex by itself. The observed magnetic phase transformations are interpreted as an evidence of competing magnetic interactions. The temperature dependent changes in the magnetic structure, derived from refinements of high-resolution neutron data, are discussed and possible mechanisms connected with the spin reorientations are described.

  • 44.
    Ivanov, Sergey
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow Russia.
    Andersson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Cedervall, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Bazuev, G. V.
    Russian Acad Sci, Inst Solid State Chem, Ural Branch, Ekaterinburg 620990, Russia.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Temperature-dependent structural and magnetic properties of R2MMnO6 double perovskites (R=Dy, Gd; M=Ni, Co)2018Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 29, nr 21, s. 18581-18592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural and magnetic properties of the Dy2CoMnO6, Dy2NiMnO6 and Gd2CoMnO6 double perovskites are investigated using X-ray powder diffraction and squid magnetometry. The materials adopt an orthorhombic structure (space ground Pnma) with disordered Co(Ni)/Mn cations, and exhibit ferrimagnetic transitions near T(C)85, 95, and 115K respectively. T-C was found to monotonously depend on the orthorhombic distortion (a-c)/(a+c) of the compounds. The crystal structure of the compounds was investigated as a function of temperature (16-1100K range), evidencing changes in the BO6 octahedron near T-C. The magnetic entropy changes are estimated for comparison of the magnetocaloric properties to those from literature.

    Ladda ner fulltext (pdf)
    fulltext
  • 45.
    Ivanov, Sergey
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia.
    Beran, Premysl
    CAS, Inst Nucl Phys, Rez, Czech Republic.
    Bush, Alexandr A.
    Moscow Technol Univ, Moscow 119454, Russia.
    Sarkar, Tapati
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Shafeie, Samrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Wang, Duo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Sanyal, Biplab
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Kvashnin, Yaroslav
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1-xScx)(2/3)W1/3O3 solid solutions2019Ingår i: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 92, nr 8, artikel-id 163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ceramic samples of the multiferroic perovskite Pb(Fe1-xScx)(2/3)W1/3O3 with 0 <= x <= 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3(_)m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B and B '' sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2/3W1/3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B ' and B '' sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1-xScx)(2/3)W1/3O3 and possibly also in the undoped PbFe2/3W1/3O3.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 46.
    Ivanov, Sergey
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Politova, Ekaterina
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Andre, Gilles
    Laboratoire Leon Brillouin, Commissariat à l'Ènergie Atomique et aux Ènergies Alternative (CEA), Saclay, Frankrike.
    Short-Range Spin Order and Frustrated Magnetism in Mn(2)InSbO(6) and Mn(2)ScSbO(6)2011Ingår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 30, s. 4691-4699Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex metal oxides Mn(2)ASbO(6) (A = In, Sc) with a corundum-related structure A(3)BO(6) were prepared as polycrystalline powders by a solid-state reaction route. Their crystal structure and magnetic properties were investigated by using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements. At room temperature, these compounds adopt a trigonal structure, space group R (3) over bar, with a = 8.9313(1) angstrom, c = 10.7071(2) angstrom (for In) and a = 8.8836(1) angstrom, c = 10.6168(2) angstrom (for Sc), which persists down to 1.6 K. The Mn and A cations were found to be randomly distributed over the A sites. The overall behavior of the magnetization of Mn(2)InSbO(6) and that of Mn(2)ScSbO(6) are quite similar. In spite of the relatively large amount of Mn ions on the A site, only short-range magnetism is observed. Neutron diffraction patterns of Mn(2)InSbO(6) showed no evidence of a long-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic peak was observed at low temperatures. The factors governing the observed structural and magnetic properties of Mn(2)ASbO(6) are discussed and compared with those of other Mn-containing complex metal oxides with a corundum-related structure. The influence of the A cation sublattice on the magnetic properties is also considered.

  • 47.
    Ivanov, Sergey
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Dept Inorgan Mat, Moscow 105064, Russia.
    Sarkar, Tapati
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bazuev, G. V.
    Russian Acad Sci, Inst Solid State Chem, Ural Branch, Ekaterinburg 620990, Russia.
    Kuznetsov, M. V.
    Russian Acad Sci, Inst Solid State Chem, Ural Branch, Ekaterinburg 620990, Russia.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Modification of the structure and magnetic properties of ceramic La2CoMnO6 with Ru doping2018Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 752, s. 420-430Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Effects of Ru doping on the structure and magnetic properties of La2CoMn1-xRuxO6 ceramics with different compositions (x = 0, 0.1, 0.2, 0.3, 0.5, 0.75, 1.0) have been investigated using a variety of complementary techniques (X-ray powder diffraction and photoelectron spectroscopy, electron microscopy, and magnetometry). Phase-pure polycrystalline samples were prepared by the conventional solid-state reaction method including high pressure (3000 kg/cm(2) ) treatment of the original mixture of reagents. X-ray diffraction analyses of the samples accompanied with Rietveld refinement suggested a change in the crystal structure upon doping: for 0 <= x <= 0.3 the structure of the samples is predominantly disordered orthorhombic (s.g. Pnma) which transformed to ordered monoclinic (s.g. P2(1)/n) for 0.5 <= x <= 1. This suggests that Ru doping induces (partial) cation order in the B-sublattice. Magnetic measurements indicated a low temperature ferromagnetic phase, and a positive value of the Curie-Weiss temperature (theta cw) was derived for all samples of composition x <= 0.75. However, the Curie temperature (T-c) and theta cw decreased with increasing Ru doping. These changes in Tc upon doping can be correlated to the changes in the nearest neighbor and next nearest neighbor exchange interactions. The sample with x =1 orders antiferromagnetically at approximately 25 K.

  • 48.
    Joshi, Deep C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Karpov Inst Phys Chem, Dept Inorgan Mat, Moscow 105064, Russia.
    Bush, A. A.
    MIREA Russian Technol Univ, Moscow 119454, Russia.
    Sarkar, Tapati
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ye, Z-G
    Simon Fraser Univ, Dept Chem, Burnaby, BC V5A 1A6, Canada;Simon Fraser Univ, 4D LABS, Burnaby, BC V5A 1A6, Canada.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Room temperature ferrimagnetism in Yb-doped relaxor ferroelectric PbFe2/3W1/3O32019Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 115, nr 7, artikel-id 072902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report ferrimagnetism and reentrant relaxor ferroelectricity near room temperature in a Yb-doped PbFe2/3W1/3O3 cubic perovskite. Structural analysis reveals the presence of a single cubic perovskite phase, with the m space group [lattice parameter: a=8.0112(3) angstrom], and partial B-site ordering. The B-site ordering yields uncompensated magnetic moments in the antiferromagnetic structure of PbFe2/3W1/3O3 and ferrimagnetism near room temperature. An excess moment of similar to 0.6 mu(B)/B-site may be estimated from magnetic hysteresis curves recorded up to 50kOe at 5K. The temperature dependent magnetodielectric study reveals a sequential phase transition from a long-range ferroelectric state (across 280K) to a short-range relaxor ferroelectric state (across 190K). The long-range ferroelectric ordering is found to be more affected by the application of external magnetic fields than the relaxor phase.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 49.
    Joshi, Deep C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ferromagnetic excess moments and apparent exchange bias in FeF2 single crystals2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 18884Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The anisotropic antiferromagnet FeF2 has been extensively used as an antiferromagnetic layer to induce exchange bias effects in ferromagnetic/antiferromagnetic bilayers and heterostructures. In this work, an apparent exchange bias occurring in the low temperature hysteresis loops of FeF2 single crystals is investigated. A detailed investigation of the hysteresis and remnant magnetization indicates that the observation of an apparent exchange bias in FeF2 stems from an intrinsic excess moment associated with a distortion of the antiferromagnetic structure of piezomagnetic origin.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 50. Jönsson, P. E.
    et al.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Wernsdorfer, W.
    Tkachuk, A.
    Barbara, B.
    Absence of conventional spin-glass transition in the Ising dipolar system LiHoxY1-xF42007Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, nr 25, s. 256403-Artikel i tidskrift (Refereegranskat)
123 1 - 50 av 115
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf