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Akhter, S., Hakim, M. A., Hoque, S. M., Mathieu, R. & Nordblad, P. (2018). Glassy behavior of diluted Cu-Zn ferrites. Journal of Magnetism and Magnetic Materials, 452, 261-265
Open this publication in new window or tab >>Glassy behavior of diluted Cu-Zn ferrites
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2018 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 452, p. 261-265Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keyword
Ferrites, Reentrant spin glass, Spin glass, Memory effect, ac susceptibility
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348826 (URN)10.1016/j.jmmm.2017.12.084 (DOI)000425547700039 ()
Available from: 2018-04-20 Created: 2018-04-20 Last updated: 2018-04-20Bibliographically approved
Ivanov, S. A., Sarkar, T., Fortalnova, E. A., Politova, E. D., Stefanovich, S. Y., Safronenko, M. G., . . . Mathieu, R. (2017). Composition dependence of the multifunctional properties of Nd-doped Bi4Ti3O12 ceramics. Journal of materials science. Materials in electronics, 28(11), 7692-7707
Open this publication in new window or tab >>Composition dependence of the multifunctional properties of Nd-doped Bi4Ti3O12 ceramics
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2017 (English)In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 28, no 11, p. 7692-7707Article in journal (Refereed) Published
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.

National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-324236 (URN)10.1007/s10854-017-6463-z (DOI)000401266700021 ()
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2017-06-19Bibliographically approved
Kumar, A. P., Ivanov, S., Ritter, C., Vijayaraghavan, R., Mathieu, R., Nordblad, P., . . . Sarma, D. D. (2017). Composition driven structural transition in La2-xSrxCuRuO6 (0 <= x <= 1) double perovskites. Journal of Alloys and Compounds, 693, 1096-1101
Open this publication in new window or tab >>Composition driven structural transition in La2-xSrxCuRuO6 (0 <= x <= 1) double perovskites
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2017 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 693, p. 1096-1101Article in journal (Refereed) Published
Abstract [en]

We report results of detailed structural investigations on the system La2-xSrxCuRuO6 (0 <= x <= 1) as a function of composition using neutron powder diffraction. Our results reveal that this series of compounds exhibit an interesting structural transition manifested through Sr doping; with Ru in single valency, in end members, and mixed valency otherwise. The end members La2CuRuO6 and LaSrCuRuO6 crystallize in monoclinic structures with space group P2(1)/n. However, the compositions with intermediate Sr doping (x = 0.2 and 0.8) crystallize in triclinic structure with space group P-1, albeit with minute distortions. The detailed structural studies by neutron powder diffraction at room temperature and at 10 K, for compositions, x = 0.2, 0.8 and 1 are presented. While magnetic measurements are indicative of ferro and antiferromagnetic like transitions for x = 0 and x > 0 respectively, neutron diffraction patterns collected at 10 K and 30 K across the characteristic transition temperature suggested by the magnetic data, do not show any extra peaks or extra intensity at lower temperature as compared to the high temperature, thus, establishing the absence of any long-range magnetic ordering in these samples.

Keyword
Oxide materials, Neutron diffraction, Crystal structure, Spin glasses
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-311473 (URN)10.1016/j.jallcom.2016.09.165 (DOI)000388610400139 ()
Funder
Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2016-12-29 Created: 2016-12-28 Last updated: 2017-11-29Bibliographically approved
Ivanov, S. A., Bush, A. A., Ritter, C., Behtin, M. A., Cherepanov, V. M., Autieri, C., . . . Mathieu, R. (2017). Evolution of the structural and multiferroic properties of PbFe2/3W1/3O3 ceramics upon Mn-doping. Materials Chemistry and Physics, 187, 218-232
Open this publication in new window or tab >>Evolution of the structural and multiferroic properties of PbFe2/3W1/3O3 ceramics upon Mn-doping
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2017 (English)In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 187, p. 218-232Article in journal (Refereed) Published
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.

Keyword
Oxides, Dielectric properties, Magnetic properties, Magnetic structures
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-316943 (URN)10.1016/j.matchemphys.2016.12.003 (DOI)000392786900026 ()
Funder
Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Knut and Alice Wallenberg FoundationCarl Tryggers foundation , CTS 12:419 13:413
Available from: 2017-03-09 Created: 2017-03-09 Last updated: 2017-11-29Bibliographically approved
Andersson, M., Mathieu, R., Normile, P. S., Lee, S. S., Singh, G., Nordblad, P. & De Toro, J. A. (2017). Magnetic properties of nanoparticle compacts with controlled broadening of the particle size distribution. Physical Review B, 95(18), Article ID 184431.
Open this publication in new window or tab >>Magnetic properties of nanoparticle compacts with controlled broadening of the particle size distribution
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2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 18, article id 184431Article in journal (Refereed) Published
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.

National Category
Engineering and Technology Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-319714 (URN)10.1103/PhysRevB.95.184431 (DOI)000405203000010 ()
Funder
Swedish Research Council
Note

Title in List of papers in Thesis: Magnetic properties of nanoparticles compacts with controlled broadening of the particle size distribution

Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-11-29Bibliographically approved
Ivanov, S. A., Ritter, C., Nordblad, P., Tellgren, R., Weil, M., Carolus, V., . . . Mathieu, R. (2017). New insights into the multiferroic properties of Mn3TeO6. Journal of Physics D: Applied Physics, 50(8), Article ID 085001.
Open this publication in new window or tab >>New insights into the multiferroic properties of Mn3TeO6
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2017 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 8, article id 085001Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keyword
electronic materials, neutron scattering, x-ray diffraction, crystal structure, magnetic properties
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-319548 (URN)10.1088/1361-6463/aa5621 (DOI)000395378000001 ()
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-11-29Bibliographically approved
Aakash, f., Nordblad, P., Mohan, R. & Mukherjee, S. (2017). Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites. Journal of Magnetism and Magnetic Materials, 441, 710-717
Open this publication in new window or tab >>Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites
2017 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 441, p. 710-717Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keyword
Ferrite, Diamagnetic, Williamson-Hall plot, Raman spectroscopy, Mossbauer spectroscopy, Super transferred hyperfine interactions
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-330522 (URN)10.1016/j.jmmm.2017.06.040 (DOI)000408015500101 ()
Available from: 2017-10-09 Created: 2017-10-09 Last updated: 2017-12-27
Tellgren, R., Ivanov, S., Bush, A. A., Kumar, P. A., Nordblad, P. & Mathieu, R. (2017). Substitution mechanism and structural study of Ag-doped LiCu2O2. Solid State Sciences, 70, 36-40
Open this publication in new window or tab >>Substitution mechanism and structural study of Ag-doped LiCu2O2
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2017 (English)In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 70, p. 36-40Article in journal (Refereed) Published
Abstract [en]

Plate-like stoichiometric crystals of Ag-doped LiCu2O2 have been grown by slowly cooling Li2CO3 center dot 4(1 - x)CuO center dot 4xAgNO(3) (0 <= x <= 0.5) melts. X-ray single crystal diffraction has shown that the crystals are isostructural with LiCu2O2 and contain around 5 at % Ag (relative to the Cu atoms). The addition of silver to lithium cuprate crystals significantly increases their electrical conductivity but has little effect on the temperature behavior of their magnetic moment. The possible substitution mechanism is determined which supports Ag+ <-> Cu+, rather than Ag+ <-> Li+ in the Ag-doped LiCu2O2 crystals.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keyword
Doped lithium cuprate, X-ray diffraction, Twin crystal, Magnetic properties, Multiferroic
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-331223 (URN)10.1016/j.solidstatesciences.2017.06.004 (DOI)000405485800005 ()
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-10-18 Created: 2017-10-18 Last updated: 2017-10-20Bibliographically approved
Sarkar, T., Ivanov, S. A., Fortalnova, E. A., Politova, E. D., Safronenko, M. G., Nordblad, P. & Mathieu, R. (2017). The role of Tb-doping on the structural and functional properties of Bi4-xTbxTi3O12 ferroelectric phases with the Aurivillius type structure. Journal of materials science. Materials in electronics, 28(6), 4914-4924
Open this publication in new window or tab >>The role of Tb-doping on the structural and functional properties of Bi4-xTbxTi3O12 ferroelectric phases with the Aurivillius type structure
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2017 (English)In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 28, no 6, p. 4914-4924Article in journal (Refereed) Published
Abstract [en]

Synthesis, crystal structure, dielectric, and magnetic properties of the Aurivillius phase Bi4-xTbxTi3O12 (x = 0.0, 0.4, 0.6, 0.8) are reported. The samples were synthesized using standard solid state reaction technique. The thermal stability of the obtained solid solutions was investigated. For x ae<currency> 0.8, the samples crystallized in an orthorhombic symmetry. All the samples showed finite second harmonic generation response indicating a non-centrosymmetric structure. The structural data could be refined using the polar orthorhombic space group B2cb. The orthorhombicity decreases with an increase in the Tb3+ concentration. The orthorhombic distortions in these compositions are related to the Bi3+-based perovskite sublattice. Our results indicate that the non-lone pair Tb3+ cations preferentially occupy the perovskite sublattice initially, but with an increase in the doping concentration they can partially substitute the Bi3+ ions in the fluorite block. Temperature dependent dielectric measurements revealed a decrease in the ferroelectric Curie temperature T-C with an increase in x from T-C = 904 K (for x = 0) to 877 K (for x = 0.4). Further increase in x led to a cross-over to a relaxor-type behavior. Magnetic measurements showed that the samples are paramagnetic down to 5 K.

Place, publisher, year, edition, pages
SPRINGER, 2017
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-320357 (URN)10.1007/s10854-016-6140-7 (DOI)000395072700052 ()
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-25Bibliographically approved
Wahlström, E., Macia, F., Boschker, J. E., Monsen, Å., Nordblad, P., Mathieu, R., . . . Tybell, T. (2017). Twinned-domain-induced magnonic modes in epitaxial LSMO/STO films. New Journal of Physics, 19, Article ID 063002.
Open this publication in new window or tab >>Twinned-domain-induced magnonic modes in epitaxial LSMO/STO films
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2017 (English)In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 19, article id 063002Article in journal (Refereed) Published
Abstract [en]

The use of periodic magnetic structures to control the magneto-dynamic properties of materials-magnonics-is a rapidly developing field. In the last decade, a number of studies have. shown that metallic films can be patterned or combined in patterns that give rise to well-defined magnetization modes,. which. are formed due to band folding or band gap effects. To explore and utilize these effects in a wide frequency range, it is necessary to pattern samples at the sub-micrometer scale. However, it is still a major challenge to produce low-loss magnonic structures with periodicities at such length scales. Here, we show that for a prototypical perovskite, La-0.7 Sr0.3MnO3, the twinned structural order can be used to induce a magnetic modulation with a period smaller than 100 nm, demonstrating a bottomup approach for magnonic crystal growth.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017
Keyword
magnonics, epitaxialLSMO/STO films, FMR, twin domains
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-327242 (URN)10.1088/1367-2630/aa70af (DOI)000402901200002 ()
Available from: 2017-08-08 Created: 2017-08-08 Last updated: 2017-11-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4561-9996

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