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Author (up) 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 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.
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 708
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Author (up) Amigó, M.L.; Ale Crivillero, M.V.; Franco, D.G.; Badía–Majós, A.; Guimpel, J.; Campo, J.; Damay, F.; Porcher, F.; Condó, A.M.; Nieva, G.
Title Intrinsic pinning by naturally occurring correlated defects in FeSe 1− x Te x superconductors Type Journal Article
Year 2017 Publication Superconductor Science and Technology Abbreviated Journal Supercond. Sci. Technol.
Volume 30 Issue 8 Pages 085010
Keywords
Abstract We study the angular dependence of dissipation in the superconducting state of FeSe and Fe(Se 1− x Te x ) through electrical transport measurements, using crystalline intergrown materials. We reveal the key role of the inclusions of the non superconducting magnetic phase Fe 1− y (Se 1− x Te x ), growing into the Fe(Se 1− x Te x ) pure β -phase, in the development of a correlated defect structure. The matching of both atomic structures defines the growth habit of the crystalline material as well as the correlated planar defects orientation.
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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 0953-2048 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 773
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Author (up) 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 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 (up) 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 Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 507 Issue Part 1 Pages
Keywords
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference
Notes Cited By :1; Export Date: 14 March 2018 Approved no
Call Number BT @ jguimpel @ Serial 790
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Author (up) Blanco, M.C.; Franco, D.G.; Jalit, Y.; Pannunzio Miner, E.V.; Berndt, G.; Paesano Jr., A.; Nieva, G.; Carbonio, R.E.
Title Synthesis, magnetic properties and Mössbauer spectroscopy for the pyrochlore family Bi2BB′O7 with B=Cr and Fe and B′=Nb, Ta and Sb Type Journal Article
Year 2012 Publication Physica B: Condensed Matter Abbreviated Journal Frontiers of Condensed Matter V (FCM 2010)
Volume 407 Issue 16 Pages 3078-3080
Keywords Pyrochlores; Crystal structure; Magnetism; Mösbauer spectroscopy; Displacive disorder
Abstract The samples Bi2BB′O7, with B=Cr and Fe and B′=Nb, Ta and Sb were prepared by solid state method. The crystallographic structure was investigated on the basis of X-ray powder diffraction data. Rietveld refinements show that the crystal structure is cubic, space group Fd-3m. The Bi3+ cation on the eight-coordinate pyrochlore A-site shows displacive disorder, as a consequence of its lone pair electron configuration. There is also a considerable A-site disorder shown by Rietveld Analysis and confirmed in the case of the iron containing samples with Mössbauer spectroscopy. The magnetic measurements show paramagnetic behavior at all temperatures for the Cr oxides. The Fe pyrochlores show antiferromagnetic order around 10 K.
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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 0921-4526 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ hernan @ Serial 647
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Author (up) 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 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 (up) 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 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 (up) 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 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+.
Address
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 (up) 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 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.
Address
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 (up) 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 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.
Address
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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