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Author Franco, D.G.; Carbonio, R.E.; Nieva, G.
Title Change in the Magnetic Domain Alignment Process at the Onset of a Frustrated Magnetic State in Ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 Double Perovskite Type Journal Article
Year 2013 Publication (up) IEEE Transactions on Magnetics Abbreviated Journal IEEE Trans. Magn.
Volume 49 Issue 8 Pages 4656-4659
Keywords coercive force; exchange interactions (electron); ferrimagnetic materials; frustration; magnetic domain walls; magnetic hysteresis; magnetic transitions; LaNi(Ni0.33Sb0.67)O6; applied magnetic field; coercive field; domain wall pinning; ferrimagnetic double perovskite; ferrimagnetic order transition; frustrated magnetic state; hysteresis data; low temperature regime; magnetic domain alignment process; magnetic exchange interactions; magnetization hysteresis loops; temperature dependence; Magnetic domain walls; Magnetic domains; Magnetic hysteresis; Magnetization; Nickel; Temperature distribution; Temperature measurement; Ferrimagnetic materials; magnetic analysis; magnetic domain walls; magnetic hysteresis
Abstract We have performed a combined study of magnetization hysteresis loops and time dependence of the magnetization in a broad temperature range for the ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 double perovskite. This material has a ferrimagnetic order transition at ~100 K and at lower temperatures (~20 K) shows the signature of a frustrated state due to the presence of two competing magnetic exchange interactions. The temperature dependence of the coercive field shows an important upturn below the point where the frustrated state sets in. The use of hysteresis data, magnetization versus applied magnetic field, together with the magnetization versus time data provides a unique opportunity to distinguish between different scenarios for the low temperature regime. From our analysis, a strong domain wall pinning results in the best scenario for the low temperature regime. For temperatures larger than 20 K, the adequate scenario seems to correspond to a weak domain wall pinning.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0018-9464 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 668
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G.
Title Magnetic Properties of the Double Perovskites LaPbMSbO6 (M = Mn, Co, and Ni) Type Journal Article
Year 2013 Publication (up) IEEE Transactions on Magnetics Abbreviated Journal IEEE Trans. Magn.
Volume 49 Issue 8 Pages 4594-4597
Keywords X-ray diffraction; cobalt compounds; lanthanum compounds; lead compounds; magnetisation; manganese compounds; nickel compounds; paramagnetic-antiferromagnetic transitions; space groups; superexchange interactions; LaPbCoSbO6; LaPbMnSbO6; LaPbNiSbO6; M2+ distribution; Rietveld analysis; Sb5+ distribution; X-ray powder diffraction pattern; antiferromagnetic coupling; antiferromagnetic transition; aqueous synthetic route; disorder; double perovskites; ferrimagnetic characteristics; interaction paths; magnetic ions; magnetic properties; monoclinic crystals; octahedral sites; polycrystals; space group P2 1/n; super-superexchange paths; Ions; Magnetic properties; Magnetization; Manganese; Nickel; Temperature measurement; X-ray diffraction; Antiferromagnetic materials; transition metal compounds
Abstract New double perovskites LaPbMSbO6, where M2+ = Mn2+, Co2+, and Ni2+, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000 °C. All samples are monoclinic, space group P21/n, as it is observed from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M2+ and Sb5+ among the two octahedral sites have 3% of disorder for M2+ = Ni2+, whereas for M2+ = Mn2+ and Co2+ less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M2 + through super-superexchange paths M2+-O2--Sb5+-O2--M2+. Transition temperatures are low: 8, 10 and 17 K for Mn2+, Co2+, and Ni2 + respectively, as a consequence of the relatively long distances between the magnetic ions M2+. Besides, for LaPbMnSbO6 a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder between Mn2+ and Sb5+. This disorder would give additional and shorter interaction paths: superexchange Mn2+-O2--Mn2+.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0018-9464 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 669
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Author Ale Crivillero, M.V.; Amigó, M.L.; Franco, D.G.; Badía-Majós, A.; Guimpel, J.; Nieva, G.
Title In Plane Vortex Dynamic Anisotropy in the Iron Deficient Fe_{1-y}Se Superconductor Type Journal Article
Year 2015 Publication (up) Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 9-14
Keywords Iron-based superconductors; Electrical transport; Critical currents
Abstract We present electrical transport measurements in the superconducting dissipative state of crystalline iron deficient Fe 1−y Se samples. These iron deficient samples were synthesized using NaCl/KCl flux and are characterized by the presence of correlated defects. The dissipation in electrical transport experiments, when the driving current is perpendicular or parallel to the crystal planes, depends strongly on the direction of the applied magnetic field , ( H=12 T), within the sample plane. There is a dissipation modulation each 60∘ due to the presence of the correlated defects. We correlate these angular dependent features with the variation of the critical currents ( Jc ) changing the direction of H confined in the crystals planes. Jc was measured from magnetization loops at fixed temperatures and angles of H always within the basal planes.
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Corporate Author Thesis
Publisher Springer US Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 708
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Author Amigó, M.L.; Ale Crivillero, M.V.; Franco, D.G.; Guimpel, J.; Nieva, G.
Title Influence of the Fe Concentration on the Superconducting Properties of Fe_{1-y}Se Type Journal Article
Year 2015 Publication (up) Journal of Low Temperature Physics Abbreviated Journal
Volume 179 Issue 1-2 Pages 15-20
Keywords Chalcogenide; Vortex pinning; Correlated defects; Electrical transport; Fe deficiency
Abstract We present a comparative study of electrical transport properties in the normal state and in the dissipative superconducting state between pure TeX -FeSe phase and Fe deficient Fe TeX Se crystals. We discuss the influence of the intergrowth of the magnetic hexagonal phase (Fe TeX Se TeX ) in Fe deficient samples when compared to pure TeX -FeSe samples. In the superconducting state, we measured the TeX -plane electrical resistivity with magnetic field up to 16 T and the electrical resistivity as a function of the angle between the TeX axis and the applied field. The angular dependence at fixed temperature below the superconducting critical temperature, TeX , is very different for both sets of crystals. The Fe deficient samples display a vortex pinning-related feature at TeX 57 TeX off the plane while the pure TeX -FeSe phase samples show the persistence of a strong angular-dependent magnetoresistance characteristic of the normal state electronic structure.
Address
Corporate Author Thesis
Publisher Springer US Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 712
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Author Haberkorn, N.; Larregola, S.; Franco, D.; Nieva, G.
Title Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single crystals Type Journal Article
Year 2009 Publication (up) JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 321 Issue 9 Pages 1133-1136
Keywords
Abstract We present a study of the magnetic properties of Gd2/3Ca1/3MnO3 single crystals at low temperatures, showing that this material behaves as an inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5 K, we have found history dependent effects in the magnetization and the presence of exchange bias. These features are compatible with microscopic phase separation in the clean Gd2/3Ca1/3MnO3 system studied. (C) 2008 Elsevier B.V. All rights reserved.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes ISI:000264170500007 Approved no
Call Number BT @ hernan @ Serial 194
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Author Franco, D.G.; Carbonio, R.E.; Kaul, E.E.; Nieva, G.
Title Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6 Type Journal Article
Year 2013 Publication (up) Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 346 Issue Pages 196-202
Keywords Ferrimagnetic; Double perovskite; Magnetic frustration; Superexchange and super-superexchange interaction; Magnetic oxide
Abstract We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in polycrystal, single crystal and thin film samples. We found that this material is a ferrimagnet ( T c ≈ 100 K ) which possesses a very distinctive and uncommon feature in its virgin curve of the hysteresis loops. We observe that bellow 20 K it lies outside the hysteresis cycle, and this feature was found to be an indication of a microscopically irreversible process possibly involving the interplay of competing antiferromagnetic interactions that hinder the initial movement of domain walls. This initial magnetic state is overcome by applying a temperature dependent characteristic field. Above this field, an isothermal magnetic demagnetization of the samples yield a ground state different from the initial thermally demagnetized one.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 666
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Author Amigó, M.L.; Crivillero, V.A.; Franco, D.G.; Badía-Majós, A.; Guimpel, J.; Nieva, G.
Title Vortex pinning by intrinsic correlated defects in Fe<inf>1-y</inf>Se Type Journal Article
Year 2014 Publication (up) Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 507 Issue Part 1 Pages
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Notes Cited By :1; Export Date: 14 March 2018 Approved no
Call Number BT @ jguimpel @ Serial 790
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Author Franco, D.G.; Fuertes, V.C.; Blanco, M.C.; Fernández-Díaz, M.T.; Sánchez, R.D.; Carbonio, R.E.
Title Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions Type Journal Article
Year 2012 Publication (up) Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.
Volume 194 Issue Pages 385-391
Keywords La3Co2SbO9; Double perovskite; Powder neutron diffraction; Rietveld refinement; Ferromagnetic; Magnetic frustration
Abstract The synthesis, structural characterization, and magnetic properties of La3Co2SbO9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P21/n. Co2+ and Sb5+ have the maximum order allowed for the La3Co2SbO9 stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) Å, b=5.6842(2) Å, c=7.9748(2) Å and β=89.999(3)°. Magnetization measurements indicate the presence of ferromagnetic correlations with TC=55 K attributed to the exchange interactions for non-linear Co2+–O–Sb5+–O–Co2+ paths. The effective magnetic moment obtained experimentally is μexp=4.38 μB (per mol Co2+), between the theoretical one for spin only (3.87 μB) and spin-orbit value (6.63 μB), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 μB/f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 671
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G.
Title Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−xCoxSb2/3O6 Type Journal Article
Year 2013 Publication (up) Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.
Volume 207 Issue Pages 69-79
Keywords Double perovskites; Neutron diffraction; Rietveld refinement; Ferrimagnetism; Magnetic frustration
Abstract We report the synthesis of double perovskites La2Ni4/3−xCoxSb2/3O6 with x=0, 1/3, 2/3 and 1 by a solid state method. Rietveld refinements of X-ray and neutron powder diffraction data show that all samples crystallize in space group P21/n, with almost perfect occupation of the 2d octahedral site with the transition metals, while all Sb5+ are randomly distributed in a 2c octahedral site. The saturation magnetization in hysteresis loops indicates that the samples are ferrimagnetic throughout all the series. Virgin magnetization curves lie outside hysteresis loops at low temperatures and thermal evolution of Hm – defined as the inflection point of these curves – follows the de Almeida–Thouless dependence for x ≠ 0 . This spin glass like behavior below 30 K is also supported by thermal evolution of the coercivity, which follows an exponential law typical of magnetic clusters, not found in the pure Ni2+ perovskite, x=0 extreme.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 670
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Author Gil, D.M.; Nieva, G.; Franco, D.G.; Gómez, M.I.; Carbonio, R.E.
Title Lead nitroprusside: A new precursor for the synthesis of the multiferroic Pb2Fe2O5, an anion-deficient perovskite Type Journal Article
Year 2013 Publication (up) Materials Chemistry and Physics Abbreviated Journal Mater. Chem. Phys.
Volume 141 Issue 1 Pages 355-361
Keywords Inorganic compounds; Magnetic materials; Powder diffraction; Thermogravimetric analysis (TGA); Magnetic properties
Abstract In order to investigate the formation of multiferroic oxide Pb2Fe2O5, the thermal decomposition of Pb[Fe(CN)5NO] has been studied. The complex precursor and the thermal decomposition products were characterized by IR and Raman spectroscopy, thermal analysis, powder X-ray diffraction (PXRD), scanning electron microscopy and magnetic measurements. The crystal structure of Pb[Fe(CN)5NO] was refined by Rietveld analysis. It crystallizes in the orthorhombic system, space group Pnma. The thermal decomposition in air produces highly pure Pb2Fe2O5 as final product. This oxide is an anion deficient perovskite with an incommensurate superstructure. The magnetic measurements confirm that Pb2Fe2O5 shows a weak ferromagnetic signal probably due to disorder in the perfect antiferromagnetic structure or spin canting. The estimated ordering temperature from the fit of a phenomenological model was 520 K. The SEM images reveal that the thermal decomposition of Pb[Fe(CN)5NO] produces Pb2Fe2O5 with small particle size.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0254-0584 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 667
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