| Records |
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 |
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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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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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 |
Journal of Low Temperature Physics |
Abbreviated Journal |
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| 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. |
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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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712 |
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Betancourth, D.; Correa, V.F.; García, D.J. |
| Title |
Evidence of a Low Energy Anisotropy in GdCoIn_5 |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of Low Temperature Physics |
Abbreviated Journal |
J. Low Temp. Phys. |
| Volume |
179 |
Issue |
1-2 |
Pages |
90-93 |
| Keywords |
Rare earth magnetism; Antiferromagnetic transition; Anisotropy |
| Abstract |
We investigate the effects of an applied magnetic field on the magnetic properties of the antiferromagnet GdCoIn 5 . The prominent anisotropy observed in the susceptibility below TN is rapidly suppressed by a field of just a few Tesla. Further evidence of this low energy-scale is obtained from magnetoresistance and magnetostriction experiments. The lattice length, particularly, shows a sudden change below 2 T when the magnetic field is applied perpendicular to the crystallographic c^ -axis. |
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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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710 |
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Betancourth, D.; Facio, J.I.; Pedrazzini, P.; Jesus, C.B.R.; Pagliuso, P.G.; Vildosola, V.; Cornaglia, P.S.; García, D. J.; Correa, V. F. |
| Title |
Low Temperature magnetic properties of GdCoIn5 |
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Journal Article |
| Year |
2015 |
Publication |
Journal of Magnetism and Magnetic Materials |
Abbreviated Journal |
J. Magn. Magn. Mater. |
| Volume |
374 |
Issue |
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Pages |
744-747 |
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| Abstract |
A comprehensive experimental and theoretical study of the low temperature properties of GdCoIn5 was performed. Specific heat, thermal expansion, magnetization and electrical resistivity were measured in good quality single crystals down to 4He temperatures. All the experiments show a second-order-like phase transition at 30 K probably associated with the onset of antiferromagnetic order. The magnetic susceptibility shows a pronounced anisotropy below T N with an easy magnetic axis perpendicular to the crystallographic ĉ-axis. Total energy GGA+U calculations indicate a ground state with magnetic moments localized at the Gd ions and allowed a determination of the Gd-Gd magnetic interactions. Band structure calculations of the electron and phonon contributions to the specific heat together with Quantum Monte Carlo calculations of the magnetic contributions show a very good agreement with the experimental data. Comparison between experiment and calculations suggests a significant anharmonic contribution to the specific heat at high temperature (View the MathML sourceT≳100K). |
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BT @ victor.correa @ |
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701 |
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Blanco, M.C.; Paz, S.A.; Nassif, V.M.; Guimpel, J.J.; Carbonio, R.E. |
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Synthesis and characterization of the new two-dimensional Heisenberg antiferromagnet double perovskite BaLaCuSbO<inf>6</inf> |
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Journal Article |
| Year |
2015 |
Publication |
Materials Letters |
Abbreviated Journal |
Dalton Transactions |
| Volume |
44 |
Issue |
23 |
Pages |
10860-10866 |
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Cited By :3; Export Date: 14 March 2018 |
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BT @ jguimpel @ |
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788 |
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Cejas Bolecek, N.R.; Dolz, M.I.; Kolton, A.; Pastoriza, H.; Beek, C.Jvander; Konczykowski, M.; Menghini, M.; Nieva, G.; Fasano, Y. |
| Title |
Geometrical Confinement Effects in Layered Mesoscopic Vortex Matter |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of Low Temperature Physics |
Abbreviated Journal |
J. Low Temp. Phys. |
| Volume |
179 |
Issue |
1-2 |
Pages |
35-41 |
| Keywords |
Vortex matter; Mesoscopic physics; Layered superconductors |
| Abstract |
We study the geometrical confinement effect in Bi 2 Sr 2 CaCu 2 O 8+δ mesoscopic vortex matter with edge-to-surface ratio of 7–12 %. Samples have in-plane square and circular edges, 30 μ m widths, and ∼ 2 μ m thickness. Direct vortex imaging reveals the compact planes of the structure align with the sample edge by introducing topological defects. The defect density is larger for circular than for square edges. Molecular dynamics simulations suggest that this density is not an out-of-equilibrium property but rather determined by the geometrical confinement. |
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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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711 |
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Celedón, C.E.; Sánchez, E.A.; Salazar Alarcón, L.; Guimpel, J.; Cortés, A.; Vargas, P.; Arista, N.R. |
| Title |
Band structure effects in the energy loss of low-energy protons and deuterons in thin films of Pt |
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Journal Article |
| Year |
2015 |
Publication |
Materials Letters |
Abbreviated Journal |
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and |
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360 |
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103-110 |
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Cited By :4; Export Date: 14 March 2018 |
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BT @ jguimpel @ |
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787 |
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Dolz, M. I.; Fasano, Y.; Cejas Bolecek, N. R.; Pastoriza, H.; Mosser, V.; Li, M.; Konczykowski, M. |
| Title |
Size-Induced Depression of First-Order Transition Lines and Entropy Jump in Extremely Layered Nanocrystalline Vortex Matter |
Type |
Journal Article |
| Year |
2015 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
| Volume |
115 |
Issue |
13 |
Pages |
137003 |
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We detect the persistence of the solidification and order-disorder first-order transition lines in the phase diagram of nanocrystalline Bi2Sr2CaCu2O8 vortex matter down to a system size of less than one hundred vortices. The temperature location of the vortex solidification transition line is not altered by decreasing the sample size although there is a depletion of the entropy jump at the transition with respect to macroscopic vortex matter. The solid order-disorder phase transition field moves upward on decreasing the system size due to the increase of the surface-to-volume ratio of vortices entailing a decrease on the average vortex binding energy. |
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American Physical Society |
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BT @ hernan @ |
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719 |
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Dolz, M.I.; Pedrazzini, P.; Pastoriza, H.; Konczykowski, M.; Fasano, Y. |
| Title |
Effect of Quenched Disorder in the Entropy-Jump at the First-Order Vortex Phase Transition of Bi{2}Sr{2}CaCu{2}O{8 + \delta } |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of Low Temperature Physics |
Abbreviated Journal |
J. Low Temp. Phys. |
| Volume |
179 |
Issue |
1-2 |
Pages |
28-34 |
| Keywords |
High Tc superconductors; First order vortex phase transition; Quenched disorder |
| Abstract |
We study the effect of quenched disorder in the thermodynamic magnitudes entailed in the first-order vortex phase transition of the extremely layered Bi 2 Sr 2 CaCu 2 O 8+δ compound. We track the temperature-evolution of the enthalpy and the entropy jump at the vortex solidification transition by means of AC local magnetic measurements. Quenched disorder is introduced to the pristine samples by means of heavy-ion irradiation with Pb and Xe producing a random columnar-track pins distribution with different densities (matching field BΦ ). In contrast with previous magneto-optical reports, we find that the first-order phase transition persists for samples with BΦ up to 100 Gauss. For very low densities of quenched disorder (pristine samples), the evolution of the thermodynamic properties can be satisfactorily explained considering a negligible effect of pinning and only electromagnetic coupling between pancake vortices lying in adjacent CuO planes. This description is not satisfactory on increasing magnitude of quenched disorder. |
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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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707 |
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| Author |
Encina, S.; Pedrazzini, P. |
| Title |
Low Temperature Thermoelectric Power of Ce(Pd{1-x}Cux)2Si2 |
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Journal Article |
| Year |
2015 |
Publication |
Journal of Low Temperature Physics |
Abbreviated Journal |
J. Low Temp. Phys. |
| Volume |
179 |
Issue |
1-2 |
Pages |
21-27 |
| Keywords |
Heavy fermions; Antiferromagnetic transition; Thermopower; Electrical resistivity |
| Abstract |
We present the thermoelectric power S(T) of the Ce(Pd 1−x Cu x ) 2 Si 2 alloy for temperatures \(1.5\,\mathrm{K} K. We observe three characteristic features across the \(0 substitution range: two positive maxima and a negative minimum, that are typical for Ce compounds that display, or lie close to, magnetism. Our analysis of the data shows that the high- T maximum is related to the Kondo effect on excited crystal-field levels, but that the low- T one cannot be simply associated with the Kondo scale, TK . We speculate that disorder induced by alloying can be at the origin of this discrepancy and can also be responsible for the low S(T) measured at low temperatures in the \(0.2 concentration range. We have extended electrical resistivity measurements on Ce(PdCu)Si 2 ( x=0.5 ) down to T∼40 mK in applied fields as high as 16 T. |
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Springer US |
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0022-2291 |
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BT @ pedrazp @ |
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706 |
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