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  • 1.
    Aakash, förnamn
    et al.
    Department of Electronics and Communication Engg., Birla Institute of Technology.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mohan, Rajendra
    Department of Physics, National Institute of Technology Patna.
    Mukherjee, Samrat
    Department of Physics, National Institute of Technology Patna.
    Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 441, s. 710-717Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In our present work, we have synthesized a series of Cd-Zn doped nickel ferrite ((Cd-0.5 Zn-x(x)) Ni0(.5)Fe(2)O(4); x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) through standard chemical co-precipitation method to study the influence of diamagnetic ions (Cd, Zn) on the magnetic properties of ferrites. XRD and Raman spectroscopy were employed for the structural characterizations. The refinement of the X-ray diffractogram data augmented by the Williamson-Hall plots showed the presence of Cd2+ vacancies and a strained crystal structure. The vibrational spectroscopy indicated the presence of lower space-group symmetry and a distorted crystal structure. Magnetic measurements showed the samples possessed low magnetic anisotropy along with a canted spin structure. The Mossbauer measurements confirmed the cation distribution and gave evidence of super transferred hyperfine interactions arising due to canted spin structure of the system.

  • 2.
    Abdu, Yassir
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Annersten, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Ericsson, Tore
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys2004Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 280, s. 243-250Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mössbauer spectroscopy in longitudinal external fields (up to 7 T) and SQUID magnetometry (up to 5 T)measurements have been carried out on mechanically alloyed (MA) g (FCC) Fe100xNix (x ¼ 21; 24, and 27 at%) alloysat room temperature. The zero-field M.ossbauer spectra of these alloys show only singlets. The high field M.ossbauerresults indicate that large amounts of the material is in the paramagnetic state, giving rise to two spectral componentswith their effective fields almost linearly depend on the external field, but with slopes that are smaller than unity. The infieldM.ossbauer spectra of the x ¼ 27 at% alloy show an additional component with a hyperfine field of E21 T, whichis attributed to Ni-rich (>30 at% Ni) clusters (domains) of ferromagnetically ordered HM phase that behavessuperparamagnetically at room temperature and shows a non-linear character in the magnetization (M–H) curves atlow fields. This HM phase is also present in the x ¼ 21 and 24 at% samples but with smaller amounts. The resultssuggest induced hyperfine fields and hence induced moments in the paramagnetic components, which increases withincreasing Ni contents. Taenite-enriched samples from the metal particles of two stony meteorites, Al Kidirate (H6)and New Halfa (L4), are also studied by high field M.ossbauer spectroscopy and the results are compared to that ofMA samples.

  • 3.
    Abdu, Yassir
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Ericsson, Tore
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Annersten, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys: Implications regarding the Fe-Ni phase diagram below 400 °C2004Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 280, nr 2-3, s. 395-403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fe–Ni alloys below the Invar region with compositions Fe100−xNix (x=21, 24, and 27 at%) were prepared by high-energy ball milling technique (mechanical alloying). The as-milled samples, characterized by X-ray diffraction and Mössbauer spectroscopy, contain a mixture of α (BCC) and γ (FCC) phases, whereas the samples annealed at 650°C for 0.5 h show a single γ (FCC) phase displaying a single line Mössbauer spectrum at room temperature (RT). At low temperature, the Mössbauer spectra of annealed Fe76Ni24 and Fe73Ni27 alloys show the existence of a magnetically split pattern together with a broad singlet, which are ascribed to a high-moment ferromagnetic Ni-rich phase and a low-moment Fe-rich phase, respectively. The Fe-rich phase in annealed Fe76Ni24 alloy, which is paramagnetic at RT, undergoes antiferromagnetic ordering at ∼40 K, estimated from the dramatic line broadening of its spectrum, giving rise to a small hyperfine field (e.g. ∼2 T at 6 K). The coexistence of these phases is attributed to phase segregation occurring in these alloys as a result of enhanced atomic diffusion. The stability of these alloys towards martensitic (FCC→BCC) transformation at low temperatures is discussed in connection with the Fe–Ni phase diagram below 400°C.

  • 4.
    Ahlberg, Martina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Papaioannou,, Evangelos Th
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Temperature dependence of magnetic properties in weakly exchange coupled Fe/V superlattices2013Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 341, s. 142-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use Fe(3)/V(x)Fe(3)/V(x) superlattices, x = 16-27 monolayers (ML) to explore the interlayer exchange coupling (IEC) as a function of both spacer layer thickness and temperature. Fe/V is a common model system for studies addressing the IEC, but the behavior in the weakly exchange coupled regime, complemented with the temperature dependence of the magnetic properties, have remained unexplored. We observe clear regions with ferro- and antiferromagnetic coupling, which is manifested in oscillations in the saturation field, the remanence and the critical temperature. The oscillation in the interlayer coupling (J') has a period of 5.8(1) ML. This is approximate to 0.8 ML smaller than observed for Fe(7)/V(x) superlattices which illustrates the influence of the magnetic layer thickness on the interlayer coupling. The temperature dependence of the remanent magnetization was proven to be significantly affected by the strength of the ferromagnetic coupling, leading to high values of the effective critical exponent beta(eff).

  • 5. Ahniyaz, Anwar
    et al.
    Seisenbaeva, Gulam A.
    Häggström, Lennart
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialfysik.
    Kamali, Saeed
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialfysik.
    Kessler, Vadim G.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Johansson, Christer
    Bergström, Lennart
    Preparation of iron oxide nanocrystals by surfactant-free or oleic acid-assisted thermal decomposition of a Fe(III) alkoxide2008Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 320, nr 6, s. 781-787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new non-hydrolytic, alkoxide-based route was developed to synthesize iron oxide nanocrystals. Surfactant-free thermal decomposition of the iron 2-methoxy-ethoxide precursors results in the formation of uniform iron oxide nanocrystals with an average size of 5.6 nm. Transmission electron microscope study shows that the nanocrystals are protected against aggregation by a repulsive surface layer, probably originating from the alkoxy-alkoxide ligands. Addition of oleic acid resulted in monodisperse nanocrystals with an average size of 4 nm. Mössbauer analysis confirmed that the nanocrystals mainly consisted of maghemite. Analysis of the magnetic hysteresis loop measurements and the zero field and field cooled measurements displayed an excellent fit to established theories for single-domain superparamagnetic nanocrystals and the size of the magnetic domains correlated well to the crystallite size obtained from transmission electron microscope.

  • 6. Ahrentorp, Fredrik
    et al.
    Astalan, Andrea
    Blomgren, Jakob
    Jonasson, Christian
    Wetterskog, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lak, Aidin
    Ludwig, Frank
    Van IJzendoorn, Leo J.
    Westphal, Fritz
    Gruettner, Cordula
    Gehrke, Nicole
    Gustafsson, Stefan
    Olsson, Eva
    Johansson, Christer
    Effective particle magnetic moment of multi-core particles2015Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 380, s. 221-226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems BNF Starch from Micromod with a median particle diameter of 100 am and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm. (C) 2014 Elsevier B.V. All rights reserved.

  • 7. Ahrentorp, Fredrik
    et al.
    Blomgren, Jakob
    Jonasson, Christian
    Sarwe, Anna
    Sepehri, Sobhan
    Eriksson, Emil
    Kalaboukhov, Alexei
    Jesorka, Aldo
    Winkler, Dag
    Schneiderman, Justin F.
    Nilsson, Mats
    Albert, Jan
    Zardán Gómez de la Torre, Teresa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strømme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Johansson, Christer
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, s. 14-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 8.
    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.

  • 9. 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.

  • 10.
    Andersson, P. H.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Nordström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    The effect of hydrogenation on the crystal structure and magnetic state in Pd3Mn2001Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 226-230, nr Part 1, s. 1040-1041Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of hydrogenation on the crystalstructure and magneticstate of Pd3Mn has been calculated using a full-potential linear augmented plane wave method in the local spin density approximation.When hydrogenated the system is observed to transform from the tetragonal Al3Zr structure to the cubic Cu3Au structure. When hydrogen is removed the system remains in a meta-stable cubic phase for an extended period of time. The structural transformations are associated with a change in the magneticstate. Our theoretical results of magnetic as well as crystalstructure stability are in agreement with experiments, especially the destabilization of the tetragonal structure for increased hydrogen concentration and complex magneticstructure of the cubic phases. The latter is analyzed in terms of Fermi surface nesting.

  • 11. Andreeva, M. A.
    et al.
    Smekhova, A. G.
    Lindgren, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Björck, Matts
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Andersson, Gabriella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Depth selective investigations of magnetic multilayers by X-ray resonant magnetic reflectivity2006Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 300, nr 1, s. e371-e374Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have measured and analyzed the X-ray resonant Bragg reflectivity spectra from BCC [Fe/Co]n superstructure near the L2,3 absorption edges of iron. The developed general computer code for the reflectivity calculations from arbitrary anisotropic multilayers allows us to test the different approaches to the treatment of the Bragg reflectivity spectra. We have proved that the observed asymmetry of the spectrum shape at the first-order Bragg peak for the right and left circular polarizations is predominantly caused by the magnetization of the central part of iron layers. The influence of interfaces is almost negligible. The fit of the energy dependence of the integral intensity of the Bragg reflection for the [Fe6/Co6]50 sample gives the value of the magnetic moment of Fe atoms in the central parts of Fe layers ∼2.6 μB, that is larger than the volume value.

  • 12. Aslibeiki, B.
    et al.
    Kameli, P.
    Ehsani, M. H.
    Salamati, H.
    Muscas, Giuseppe
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Agostinelli, E.
    Foglietti, V.
    Casciardi, S.
    Peddis, D.
    Solvothermal synthesis of MnFe2O4 nanoparticles: The role of polymer coating on morphology and magnetic properties2016Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 399, s. 236-244Artikel i tidskrift (Refereegranskat)
  • 13.
    AYADI, M
    et al.
    Univ Paris-sud.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    FERRE, J
    Univ Paris-sud.
    MAUGER, A
    Univ Paris-sud.
    TRIBOULET, R
    SPIN-GLASS FREEZING IN CD1-XMNXTE1986Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 54-7, s. 1223-1224Artikel i tidskrift (Refereegranskat)
  • 14. BAJOREK, A
    et al.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    SPASOJEVIC, V
    RODIC, D
    KUSIGERSKI, V
    ON EXCHANGE MECHANISM IN HG1-XMNXS1994Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 131, s. 363-368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic susceptibility of Hg0.95Mn0.05S and Hg0.90Mn0.10S was measured by the SQUID technique. The experimental data were compared with the extended nearest neighbour pair approximation (ENNPA) calculation. The long range exchange interaction J = J(NN)R(-n), with the exponent n = 4, was found for both samples. The nearest neighbour exchange integral J(NN) was found to be around two times smaller than the effective exchange integral J(eff). The small value of the exponent n, which is a characteristic of the narrow gap semimagnetic semiconductors (SMSC’s), as well as the small J(NN)/J(eff) ratio, show the importance of a long-range exchange mechanism.

  • 15. Banerjee, Mitali
    et al.
    Mookerjee, Abhijit
    Majumdar, A. K.
    Banerjee, Rudra
    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.
    Nigam, A. K.
    Magnetism in FeNiW disordered alloys: Experiment and theory2010Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 322, nr 21, s. 3558-3564Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report here an experimental study of magnetization of FeNiW alloys at different compositions. We have studied variation of magnetization with temperature (at low external fields) and magnetic field (at low temperatures). The alloy shows para to ferromagnetic transitions across the composition range. We do not find any indication of the spin-glass phase. We have supplemented the experimental work with theoretical analysis using the first-principles tight-binding linear muffin-tin orbitals based augmented space recursion method. Our theoretical estimates of magnetic moment and Curie temperatures agree well with experiment. Our mean-field phase analysis also does not indicate the possibility of a spin-glass.

  • 16.
    Barwal, Vineet
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Husain, Sajid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Fasta tillståndets fysik.
    Gupta, Nanhe Kumar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Hait, Soumyarup
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Pandey, Lalit
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Structural and magneto-transport properties of co-sputtered MnAl thin films2020Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 503, artikel-id 166654Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the structural and magneto-transport properties of co-sputtered MnAl alloy thin films grown on Si (1 0 0) at various substrate temperatures (T-s) ranging from room temperature to 500 degrees C. Analyses of the X-ray diffraction and DC-Magnetization data reveal that as the T-s of the films is changed, the volume fraction of ferromagnetic tau-MnxAl100-x (50 < x < 60) metastable phase retained in the films changes from 3.7 to 9.5% and the remaining fraction comprises of non-magnetic beta-MnAl and gamma(2)-phases. The temperature-dependent longitudinal resistivity variation demonstrates a semi-metallic nature in all these films. The temperature dependence of Hall Effect data further corroborates this semi-metallic behavior. The magnetoresistance (MR) response of these films is measured in the range of 10-300 K, both in the in-plane as well as out-of-plane magnetic field configurations. The out-of-plane MR is significantly larger than in-plane MR due to electron-hole compensation (which stems from mull-band effects) which is discussed further by plotting the Kohler's plot for the thin films.

  • 17. Bau, L. V.
    et al.
    Khiem, N. V.
    Phuc, N. X.
    Hong, L. V.
    Nam, D. N. H.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Observation of mixed-phase behavior in the Mn-doped cobaltite La0.7Sr0.3Co1-xMnxO3 (x=0-0.5)2010Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 322, nr 6, s. 753-755Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Studies on La0.7Sr0.3Co1-xMnxO3 (x=0-0.5) compounds evidence that the interaction between Mn and Co ions in this system is antiferromagnetic super-exchange and not ferromagnetic (FM) double-exchange (DE). As a result, antiferromagnetism and magnetic glassiness develop steadily with increasing Mn content and the system becomes a spin glass at x similar to 0.1. Analyses of high-field magnetization data indicate that the system consists of two major phases: a metallic FM phase which magnetically saturates in rather low field, and an insulating non-FM phase which has a linear dependence of magnetization on magnetic field. In the low doping regime, the fraction of the non-FM component expands with temperature at the expense of the FM phase and becomes maximal at T-C. Ferromagnetism reappears in highly doped (x >= 0.2) compounds due to the presence of DE interaction between the Mn ions. The small volume fraction of the FM phase derived from the M(H) data in high field region supports the coexistence of insulating and FM behaviors in the highly doped samples. (C) 2009 Elsevier B.V. All rights reserved.

  • 18.
    Behera, Nilamani
    et al.
    Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
    Kumar, Ankit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Pandya, Dinesh K.
    Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
    Chaudhary, Sujeet
    Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
    Anisotropic magnetic damping studies in β-Ta/2D-epitaxial-Py bilayers2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 444, s. 256-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the anisotropy of the effective damping (αeff) in the sputtered β-Ta(6 nm)/2D-epitaxial-Py(tPy = 3–10 nm) bilayers. In-plane field orientation dependent FMR measurements revealed a prominent anisotropy in αeff, which is ascribed to the spin wave induced spin pumping from Py to β-Ta in β-Ta/epi-Py system. The results especially suggest that at lower tPy a relatively larger αeff and its anisotropic nature are present in β-Ta/epi-Py bilayers as compared to bare epi-Py, which are unlikely at higher tPy. This is possibly due to both spin pumping which stems from in-plane spin waves associated with two magnon scattering mechanism and interface induced anisotropy from heavy metals like β-Ta at β-Ta/Py interface. The in-plane Hr vs. φ reveals clear anisotropy behavior at tPy ≤ 4 nm.

  • 19.
    BELANGER, DP
    et al.
    UCSB.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    KING, AR
    UCSB.
    JACCARINO, V
    UCSB.
    LUNDGREN, L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    BECKMAN, O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    CRITICAL-BEHAVIOR IN ANISOTROPIC ANTI-FERROMAGNETS1983Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 31-4, s. 1095-1096Artikel i tidskrift (Refereegranskat)
  • 20.
    Benhouria, Y.
    et al.
    Univ Moulay Ismail, Unit Associated CNRST URAC 08, Fac Sci, LP2MS,Phys Dept, BP 11201, Meknes, Morocco.
    Bouziani, I.
    Univ Moulay Ismail, Unit Associated CNRST URAC 08, Fac Sci, LP2MS,Phys Dept, BP 11201, Meknes, Morocco.
    Essaoudi, I.
    Univ Moulay Ismail, Unit Associated CNRST URAC 08, Fac Sci, LP2MS,Phys Dept, BP 11201, Meknes, Morocco;Uppsala Univ, Condensed Matter Theory Grp, Dept Phys & Astron, S-75120 Uppsala, Sweden.
    Ainane, Abdelmajid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Moulay Ismail, Unit Associated CNRST URAC 08, Fac Sci, LP2MS,Phys Dept, BP 11201, Meknes, Morocco;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Quantum Monte Carlo study of dynamic magnetic properties of nano-graphene2018Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 460, s. 223-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using the Quantum Monte Carlo simulation (QMCS), the dynamic blocking temperature of a nanographene bilayer has been investigated within the framework of the Transverse Ising Model (TIM) with mixed spins, under the existence of the time-dependent oscillating longitudinal magnetic field (h(t) = h(b) + h(0)cos(omega t)) and the transverse field (Omega). The influence of the time-dependent oscillating longitudinal magnetic field, the period of magnetic field (tau) and the transverse field (Omega) on the thermal behavior of the total longitudinal and transverse dynamic order parameters, the total dynamic magnetic susceptibility and the dynamic hysteresis of the nano-graphene bilayer are also studied. As results, we remark the appearance of multiple hysteresis loops and the system exhibits the superparamagnetic behavior at the dynamic blocking temperature.

  • 21.
    Bergman, Anders
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Nordström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Klautau, Angela Burlamaqui
    Frota-Pessoa, Sonia
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Magnetism of Co overlayers and nanostructures on W(001): A first principles study2008Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 320, nr 6, s. 1173-1179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic properties of Co nanostructures and a Co monolayer on W(001) have been studied in the framework of density functional theory. Different geometries such as planar and three-dimensional clusters have been considered, with cluster sizes varying between 2 and 13 atoms. The calculations were performed using the real-space linear muffin-tin orbital method (RS-LMTO-ASA). With respect to the stability of the magnetic state, we predict an antiferromagnetic (AFM) structure for the ground state of the planar Co clusters and a ferromagnetic (FM) state for the three-dimensional clusters. For the three-dimensional clusters, one of the AFM arrangements leads to frustration due to the competing FM and AFM exchange interactions between different atoms in the cluster, and gives rise to a non-collinear state with energy close to that of the FM ground state. The relative role of the Co-Co and Co-W exchange interactions is also investigated.

  • 22.
    Björck, Matts
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Andersson, Gabriella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Hedlund, M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Magnetic moments in FeCo/Pt (001) superlattices2008Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 320, nr 21, s. 2660-2664Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The element specific spin and orbital moments for Fe and Co in Fe40Co60/Pt (001) superlattices, with layer thicknesses d(FeCo) = 4-10 ML and d(Pt) = 8 ML, have been studied by X-ray magnetic circular dichroism with focus on the interfacial magnetic moments of the Fe40Co60 layers. The spin moments of Fe and Co showed the same relative decrease at the interfaces with respect to the bulk alloy. The change at the interface was found to be -0.9(1) of the bulk alloy spin moment. The orbital moment for Fe also decreased at the interfaces, whereas the Co orbital moment did not show any appreciable change at the interfaces. In addition, SQUID measurements of the total magnetization allowed the extraction of the induced Pt magnetic moment, which was found to be 0.6(3)mu B/atom and is discussed with respect to previous studies.

  • 23.
    Björck, Matts
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik III.
    Andersson, Gabriella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Lindgren, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Wäppling, Roger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Stanciu, Victor
    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.
    Element-specific magnetic moment profile in BCC Fe/Co superlattices2004Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 284, s. 273-280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BCC Fe/Co superlattices with individual layer thicknesses in the range of 2–9 monolayers have been investigated byX-ray magnetic circular dichroism in combination with SQUID magnetometry in order to study the magnetic momentdistribution in the superlattices. The magnetic moment for Co was found to remain constant, within 0:1 mB=atom, at1:6 mB=atom for all the superlattices. The Fe atoms at the interface have an enhanced moment of about 3:0 mB=atom. Inaddition, a complex dependence of the size of the moments on the thickness of the Fe layer was found and attributed tointerface roughness effects. Element-specific hysteresis curves were also recorded. These measurements show that themagnetic moments of Fe and Co were, as expected, coupled during reversal of the magnetic moment direction.

  • 24.
    Björck, Matts
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Pärnaste, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Marcellini, Moreno
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Andersson, Gabriella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    The effect of strain and interfaces on the orbital moment in Fe/V superlattices2007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 313, nr 1, s. 230-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dependence of the Fe orbital moment on strain and interfaces in Fe/V superlattices has been investigated by X-ray magnetic circular dichroism (XMCD). The orbital moment was determined to be lower at the interfaces than in the bulk, which we attribute to Fe–V hybridization. An enhancement of the orbital moment with increasing strain in the Fe layers was observed. This enhancement is attributed to an unquenching of the orbital moment. Consequently, the orbital moment of Fe in Fe/V is concluded to be influenced by two competing parameters. It is lowered by increasing interface density, and enhanced by increasing strain.

  • 25. Bouhou, S.
    et al.
    Essaoudi, I.
    Ainane, A.
    Saber, M.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Dujardin, F.
    Phase diagrams of diluted transverse Ising nanowire2013Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 336, s. 75-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the phase diagrams of diluted Ising nanowire consisting of core and surface shell coupling by J(cs) exchange interaction are studied using the effective field theory with a probability distribution technique, in the presence of transverse fields in the core and in the surface shell. We find a number of characteristic phenomena. In particular, the effect of concentration c of magnetic atoms, the exchange interaction core/shell, the exchange in surface and the transverse fields in core and in surface shell of phase diagrams are investigated.

  • 26. Bouhou, S.
    et al.
    Zaim, A.
    Ainane, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Kerouad, M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Magnetic properties of a ferromagnetic thin film with four spin interaction: A Monte Carlo simulation study2013Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 339, s. 127-132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monte Carlo simulation has been used to study the critical behaviors and the magnetic properties of a ferromagnetic thin Ising film with a plaquette four spin interaction. The effects of the ratio r(s) =J(s)/J of the surface exchange interaction to the bulk one and the four spin interaction on phase diagrams are investigated. A number of characteristic behaviors have been found, which include the first-and second-order phase transitions, thus also the tricritical points, triple point and isolated critical point. 

  • 27.
    Bouziani, I
    et al.
    Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco.
    Benhouria, Y.
    Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco.
    Essaoudi, I
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco.
    Ainane, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Half metallic ferromagnetic behavior in (Ga, Cr)N and (Ga, Cr, V)N compounds for spintronic technologies: Ab initio and Monte Carlo methods2019Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 477, s. 220-225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, we investigate the magnetic and electronic properties of GaN doped with simple and double impurities utilizing Ab initio and Monte Carlo studies. We have predicted that (Ga, Cr)N and (Ga, Cr, V)N compounds exhibit ferromagnetic- and halfmetallic-behavior with 100% spin polarization at the Fermi level. Moreover, we have found that Ga1-xCrxN and Ga1-2xCrxVxN (x = 0.04, 0.05 and 0.06) show a second order ferromagnetic transition and that their T-c is above room temperature. These predictions make (Ga, Cr)N and (Ga, Cr, V)N compounds strong candidates for spintronic technologies.

  • 28.
    Bouziani, I.
    et al.
    Univ Moulay Ismail, LP2MS, Fac Sci, Unite Associee CNRST URAC 08,Phys Dept, BP 11201, Meknes, Morocco.
    Benhouria, Y.
    Univ Moulay Ismail, LP2MS, Fac Sci, Unite Associee CNRST URAC 08,Phys Dept, BP 11201, Meknes, Morocco.
    Essaoudi, I.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ainane, Abdelmajid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Magnetoelectronic properties of Vanadium impurities co-doped (Cd, Cr)Te compound for spintronic devices: First principles calculations and Monte Carlo simulation2018Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 466, s. 420-429Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have applied the first-principles calculations to investigate magnetoelectronic properties of Vanadium impurities co-doped (Cd, Cr)Te compound for spintronic devices. The ferromagnetic (FM) nature in (Cd, Cr)Te compound co-doped with V atoms has been found, and the mechanism responsible for this behavior has been considered to be the double exchange. Moreover, the Curie-temperature calculation reveals that the stability's field of the FM-phase rises with rising both the concentration of Cr and V atoms above ambient temperature. This system presents the half-metallic character where its polarization of spin is total at the Fermi level, and its total magnetic moment is principally induced by Cr and V elements. The spin-orbit coupling (SOC) typically play an important role in the electronic structure calculations due to both the concentration of Cr and V impurities. In addition to that, our results have been confirmed by the calculation of magnetization and susceptibility using the Monte Carlo simulation.

  • 29.
    Carva, Karel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Turek, Ilja
    Out-of-plane spin-transfer torques: first-principles study2010Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 322, nr 9-12, s. 1085-1087Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spin-transfer torques in layered structures are studied with particular attention to their direction. Their direction is in spin valves determined mainly by the properties of the free layer and its interfaces. Situations which lead to a significant component of the torque in the direction perpendicular to both magnetizations present in the spin valve (out-of-plane torque) are described and analyzed. This component may arise from the transmitted spin current, as is demonstrated for a Cu vertical bar Ni vertical bar Cu(001) based system, or from the reflected spin current, which is found to be particularly high for systems with Cr vertical bar Co2MnSi interface. Ab initio calculations were performed for these systems employing the local spin density approximation (LSDA) and the linear muffin-tin orbital (LMTO) method. Information about the direction of the torque was obtained from the spin-mixing conductance.

  • 30.
    Cedervall, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Andersson, Mikael Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Industriell teknik.
    Iusan, Diana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Delczeg-Czirjak, Erna Krisztina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Jansson, Ulf
    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.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Magnetic and mechanical effects of Mn substitutions in AlFe2B22019Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 482, s. 54-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical and magnetic properties of the newly discovered MAB-phase class of materials based upon AlFe2B2 were investigated. The samples were synthesised from stoichiometric amounts of all constituent elements. X-ray diffraction shows that the main phase is orthorhombic with an elongated b-axis, similar to AlFe2B2. The low hardness and visual inspection of the samples after deformation indicate that these compounds are deformed via a delamination process. When substituting iron in AlFe2B2 with manganese, the magnetism in the system goes from being ferro- to antiferromagnetic via a disordered ferrimagnetic phase exhibited by AlFeMnB2. Density functional theory calculations indicate a weakening of the magnetic interactions among the transitions metal ions as iron is substituted by manganese in AlFe2B2. The Mn-Mn exchange interactions in AlMn2B2 are found to be very small.

  • 31. 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)
  • 32. CHIRWA, M
    et al.
    LUNDGREN, L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    BECKMAN, O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    MAGNETIC SPECIFIC-HEAT OF FEF2 NEAR TN1980Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 15-8, s. 457-458Artikel i tidskrift (Refereegranskat)
  • 33.
    Colarieti-Tosti, M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Nordström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Brooks, Michael S. S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Wills, J. M.
    Crystal field levels in lanthanide systems2001Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 226-230, nr Part 1, s. 1027-1028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crystalfieldlevels in lanthanide compounds have been calculated by first-principles theory, combining the strength of the standard model for rare earths in treating the localized 4f electrons and the power of Density Functional Theory in describing the, weakly correlated, delocalized, electrons. The stability of our calculations has been checked against changes of the constraints in the Full Potential-LMTO implementation. The assumption of weak 4f–4f inter-atomic interactions has also been checked by means of supercell calculations. Suggestions for the treatment of magnetic systems on a similar basis are given.

  • 34.
    Delavari, Hamid H.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Hosseini, Hamid R. Madaah
    Wolff, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Modeling of self-controlling hyperthermia based on nickel alloy ferrofluids: Proposition of new nanoparticles2013Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 335, s. 59-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to provide sufficient heat without overheating healthy tissue in magnetic fluid hyperthermia (MFH), a careful design of the magnetic properties of nanoparticles is essential. We perform a systematic calculation of magnetic properties of Ni-alloy nanoparticles. Stoner-Wohlfarth model based theories (SWMBTs) are considered and the linear response theory (LRT) is used to extract the hysteresis loop of nickel alloy nanoparticles in alternating magnetic fields. It is demonstrated that in the safe range of magnetic field intensity and frequency the LRT cannot be used for the calculation of the area in the hysteresis for magnetic fields relevant for hyperthermia. The best composition and particle size for self-controlling hyperthermia with nickel alloys is determined based on SWMBTs. It is concluded that Ni-V and Ni-Zn are good candidates for self-controlling hyperthermia.

  • 35.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Ainane, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Ahuja, R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Reentrant phenomenon in a transverse spin-1 Ising nanoparticle with diluted magnetic sites2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 442, s. 53-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, we have examined the influence of surface shell exchange coupling on the magnetic properties of a diluted ferromagnetic spin- 1 Ising nanocubic particle, by employing the effective-field theory with correlations based on the probability distribution technique. Some interesting results have been found such as, a tricritical point, a triple point, an isolated critical point, reentrant and even double reentrant phenomena, S-, R- and Q-type behaviors, as well as, both first-and second-order phase transitions as it is confirmed by the free energy. In addition, when the interactions are low between the surface shell sites, quadruple hysteresis loops can be seen in the system.

  • 36.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Ainane, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    A theoretical study of the hysteresis behaviors of a transverse spin-1/2 Ising nanocube2016Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 413, s. 30-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The applied magnetic field dependencies of the surface shell, core and total magnetizations of a transverse spin -I Ising nanocube are investigated within the effective -field theory with correlations, based on the probability distribution technique, for both ferro- and antiferromagnetic exchange interactions. We have found that interfacial coupling has a strong effect on the shape and the number of hysteresis loops and also on the coercive field and remanent magnetization behaviors. Furthermore, when the temperature exceeds a critical one, the coercivities of the core, the surface shell and the system become zero.

  • 37. Emmel, M.
    et al.
    Alfonsov, A.
    Legut, D.
    Kehlberger, A.
    Vilanova, E.
    Krug, I. P.
    Gottlob, D. M.
    Belesi, M.
    Buechner, B.
    Klaeui, M.
    Oppeneer, Peter M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Wurmehl, S.
    Elmers, H. J.
    Jakob, G.
    Electronic properties of Co2FeSi investigated by X-ray magnetic linear dichroism2014Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 368, s. 364-373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present experimental XMLD spectra measured on epitaxial (001)-oriented thin Co2FeSi films, which are rich in features and depend sensitively on the degree of atomic order and interdiffusion from capping layers. Al- and Cr-capped films with different degrees of atomic order were prepared by DC magnetron sputtering by varying the deposition temperatures. The local structural properties of the film samples were additionally investigated by nuclear magnetic resonance (NMR) measurements. The XMLD spectra of the different samples show clear and uniform trends at the L-3,L-2 edges. The Al-capped samples show similar behavior as previous measured XMLD spectra of Co2FeSi0.6Al0.4. Thus, we assume that during deposition Al atoms are being implanted into the subsurface of Co2FeSi. Such an interdiffusion is not observed for the corresponding Cr-capped films, which makes Cr the material of choice for capping Co2FeSi films. We report stronger XMLD intensities at the L-3,L-2 Co and Fe egdes for films with a higher saturation magnetization. Additionally, we compare the spectra with ab initio predictions and obtain a reasonably good agreement. Furthermore, we were able to detect an XMCD signal at the Si Ledge, indicating the presence of a magnetic moment at the Si atoms.

  • 38.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Vennström, Marie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Ronneteg, Sabina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Complex magnetic properties of Mn3Ni20P6 and ferromagnetic structure of the new isostructural compound Mn3Pd20P62007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 308, nr 2, s. 203-209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new compound, Mn3Pd20P6, has been synthesized and the crystal and magnetic structures have been determined by neutron powder diffraction. The crystal structure is cubic, with a = 11.9563(2) angstrom, space group Fm (3) over barm, and is isostructural to Mn3Ni20P6, a ternary ordering variant of the Cr23C6-type structure. The magnetic properties of Mn3Pd20P6 and Mn3Ni20P6 were studied by magnetization measurements. For Mn3Pd20P6 a transition, suggested to be of first order, to a ferromagnetic structure takes place at 110 K, whereas the saturation magnetization shows unusual temperature dependence. Magnetization vs. field loops show very weak coercivity, and the magnitude of the saturation magnetization agrees well with parallel Mn magnetic moments on two different sublattices of 4.24(8) mu(B), and 2.88(8) mu(B), respectively, found by neutron powder diffraction at 10 K. Magnetization vs. temperature measurements for Mn3Ni20P6 do not show a well-defined transition temperature, but show signatures of magnetic order with small excess magnetic moments aligned by the applied field below about 240 K. Further, signatures of a spin reorientation process at around 30 K are noted.

  • 39. Garg, K. B.
    et al.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Heinonen, M.
    Panwar, N.
    Sen, V.
    Bondino, F.
    Magnano, E.
    Carleschi, E.
    Parmigiani, F.
    Agarwal, S. K.
    Study of Sb substitution for Pr in the Pr0.67Ba0.33MnO3 system2009Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 321, nr 4, s. 305-311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the effect of Sb substitution for Pr in the hole-doped system Pr0.67Ba0.33MnO3 (PBMO) for different doping levels of Sb. The two electrical resistivity transitions observed in the pristine sample PBMO shift to low temperatures on Sb doping with an overall increase in the electrical resistivity. The significant local lattice distortion and the grain boundary effects caused by the large cation size mismatch between Pr3+ and Sb3+ suppresses the double-exchange (DE) interaction and enhances the super-exchange (SE) interaction. The compounds show a significant and increasing value of magnetoresistance at temperatures below the Curie temperature, not expected from the DE model. The Curie temperature decreases with increase in Sb content but the saturation magnetization is little affected by the substitution. The spins, however, stay well aligned in the low-temperature regime. Our X-ray near-edge absorption spectra (XANES) and core level photoemission (XPS) data clearly show the Sb cation to be in +3 state and rule out any possibility of e-doping in our compounds.

  • 40. Ghosh, S.
    et al.
    Sanyal, Biplab
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialteori.
    Das, G. P.
    Structural, electronic and magnetic properties of Cr-doped Cd12S12 clusters: A density functional investigation2010Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 322, nr 6, s. 734-742Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have carried out first-principles density functional investigation of Cd12S12 cluster doped with one (monodoped) and two (bidoped) Cr-atoms, to explore the manifestation of novel magnetism in this family of stable II-VI semiconducting clusters. Different types of possible configurations of the dopant e.g. substitutional, exohedral, endohedral and substitutional-exohedral have been considered. Both for monodoped and bidoped clusters, substitutional doping corresponds to the ground state. Incase of bidoped clusters, the coupling is found to be short-ranged, that depends on the Cr-Cr separation and the local environment. The main competing factors stabilizing ferromagnetic (FM) state in this class of doped nanoclusters are: (a) the FM interaction between two Cr atoms via S atom due to strong p-d hybridization and (b) the short range Cr-Cr direct antiferromagnetic (AFM) interaction. When additional hole is introduced in the system by substituting S with P, in substitutional bidoped clusters, FM state is found to be the ground sate. (C) 2009 Elsevier B.V. All rights reserved.

  • 41.
    GRANBERG, P
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    LUNDGREN, L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    NONEQUILIBRIUM RELAXATION IN A CU(MN) SPIN-GLASS1990Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 92, s. 228-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The zero-field dynamics of a Cu(10 at% Mn) spin glass system has been investigated by means of zero-field-cooled magnetization measurements. By subjecting the sample to specific temperature variations just before the field application, new information about the nature of the spin glass phase is obtained. The results are in accord with some predictions from domain theories on the behaviour of the magnetic relaxation in spin glasses. Specifically, the experimental results support the prediction that the spin glass dynamics is governed by an interplay between a growing domain size and the overlap length.

  • 42.
    GUNNARSSON, K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    ANDERSSON, JO
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    SVEDLINDH, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    NORDBLAD, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    LUNDGREN, L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    KATORI, HA
    ITO, A
    EQUILIBRIUM AND NONEQUILIBRIUM MAGNETIC-BEHAVIOR OF A REENTRANT ISING SPIN-GLASS1992Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 104, s. 1607-1608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reentrant Ising spin glass Fe0.62Mn0.38TiO3 has been investigated using SQUID magnetometry. The system is antiferromagnetic below T(N)(H = 0) = 33 K, and enters a mixed antiferromagnetic/spin glass phase below T(g)(H = 0) = 25.8 K. Within the concept of a recent mean field model, a ratio T(N)(0)/T(g)(0) close to unity indicates both intra- and interlayer frustration. The existence of an overlap length, l(DELTA-T), below which equilibrium spin correlations at temperatures T and T + DELTA-T are indistinguishable has been verified by magnetic relaxation experiments on this spin glass system.

  • 43.
    Hanson, Maj
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden.
    Brucas, Rimantas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Domain walls in Fe(001) bicrystals-thickness dependence and field-induced transitions2007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    ABSTRACT: Magnetic domain walls (DW's) formed at the grain boundary (GB) of epitaxial bicrystal Fe(001) films, thickness t=50 and 70nm, were studied by magnetic force microscopy. The “as-grown” samples displayed DW's with different magnetic contrast profiles yielding a single peak for t=50nm and a double peak with a change of sign at the centre of the wall for t=70nm. For t=50nm the wall is characterised as an asymmetric Bloch wall. The double peak of the 70nm thick film transformed into a single peak characteristic for a charged wall, when a field of 30mT was applied along the GB. At remanence this domain wall relaxed to a regular Bloch wall divided into segments of alternating signs.

    Article · Mar 2007 · Journal of Magnetism and Magnetic Materials

  • 44.
    Hanson, Maj
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden.
    Brucas, Rimantas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kazakova, O.
    Effects of size and interactions on the magnetic behaviour of elliptical (001)Fe nanoparticles2007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    ABSTRACT: Arrays of elliptical particles with aspect ratio 1:3 and short axes 50, 100 and 150 nm were prepared by electron-beam lithography and ion-beam milling of epitaxial (0 0 1)Fe films of thicknesses 10 and 20 nm. The domain state of an individual particle imaged by magnetic force microscopy in zero field after demagnetization was observed to change from being bi-domain or multidomain (MD) to stable single domains (SD) as the lateral size and film thickness were decreased. The critical size for SD formation was found to be close to the actual lateral sizes of 100 nm×300 nm and 150 nm×450 nm for the thicknesses of 20 and 10 nm, respectively. Only in the 10 nm thick ellipses of lateral size 100 nm×300 nm, the magnetization reversal may take place through coherent rotation. For all other investigated samples, the experimental switching field is lower than what would be required for this process.

    Article · Sep 2007 · Journal of Magnetism and Magnetic Materials

  • 45.
    Hanson, Maj
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden.
    Brucas, Rimantas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kazakova, O.
    Effects of size and interactions on the magnetic behaviour of elliptical (001)Fe nanoparticles2007Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766Artikel i tidskrift (Refereegranskat)
  • 46.
    Holmström, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Bergqvist, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Skubic, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Kondenserade materiens teori (Fysik IV).
    Structural and magnetic aspects of multilayer interfaces2004Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 272-276, nr Suppl., s. E941-E942Artikel i tidskrift (Refereegranskat)
  • 47.
    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.

  • 48.
    Husain, Sajid
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Barwal, Vineet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Kumar, Ankit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gupta, Rahul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Behera, Nilamani
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Hait, Soumyarup
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Gupta, Nanhe Kumar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Multi-jump magnetization switching in Co2FeAl full Heusler alloy thin films: Experiments and simulations2019Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 486, artikel-id 165258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Co2FeAl (CFA) thin films of 50 nm thickness have been grown on MgO (001) single crystal substrates at room temperature with and without post-annealing (PA) at 300 degrees C and 400 degrees C using dual ion-beam sputtering technique. The XRD pattern of the as-grown film revealed that CFA grows with preferred crystallographic orientation on the MgO (001) substrate. Temperature dependent anisotropy measurements on PA films revealed a dominating contribution from cubic anisotropy as confirmed by the analysis of azimuthal angle dependent longitudinal in-plane magneto-optical Kerr effect (MOKE) measurements. The contributions from the cubic and uniaxial anisotropies have also been quantified employing ferromagnetic resonance spectroscopy. Magnetization reversal is accompanied with a plateau in the MOKE hysteresis recorded at various azimuthal angles in the in-plane applied magnetic field configuration. The occurrence of the observed plateau is explained by the presence of a combination of domain walls such as 90 degrees, 135 degrees and 180 degrees domain walls and/or complex domains which is supported by results from micromagnetic simulations. These results demonstrate the feasibility of manipulating the magnetization switching in one of the two ferromagnetic electrodes of the magnetic tunnel junction devices based on Heusler alloy ferromagnetic films.

  • 49.
    Husain, Sajid
    et al.
    Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
    Kumar, Ankit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Akansel, Serkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Chaudhary, Sujeet
    Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
    Anomalous Hall effect in ion-beam sputtered Co2FeAl full Heusler alloy thin films2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 442, s. 288-294Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Investigations of temperature dependent anomalous Hall effect and longitudinal resistivity in Co2FeAl (CFA) thin films grown on Si(1 0 0) at different substrate temperature Ts are reported. The scaling of the anomalous Hall conductivity (AHC) and the associated phenomenological mechanisms (intrinsic and extrinsic) are analyzed vis-à-vis influence of Ts. The intrinsic contribution to AHC is found to be dominating over the extrinsic one. The appearance of a resistivity minimum at low temperature necessitates the inclusion of quantum corrections on account of weak localization and electron-electron scattering effects whose strength reduces with increase in Ts. The study establishes that the optimization of Tsplays an important role in the improvement of atomic ordering which indicates the higher strength of spin-orbit coupling and leads to the dominant intrinsic contribution to AHC in these CFA full Heusler alloy thin films.

  • 50.
    Höglin, Viktor
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Cedervall, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Andersson, Mikael Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sarkar, Tapati
    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.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Irreversible structure change of the as prepared FeMnP1−xSix-structure on the initial cooling through the curie temperature2015Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 374, s. 455-458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    FeMnP0.75Si0.25 experiences a first order para- to ferromagnetic transition at about 200 K. In common with some other alloy compositions crystallizing in the Fe2P structure, the magnetic transition of the as prepared alloy occurs at a lower temperature than on subsequent cooling events. This virgin effect is found to be accompanied by a magnetostrictively induced irreversible structure change that persists on succeeding cooling heating cycles. These findings provide means to understand and control the thermal hysteresis of the (Fe1-xMnx)(2)P1-ySiy alloy system which is a promising material class for use in magnetocaloric refrigerators.

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