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Author (up) de la Cruz, F.; López, D.; Nieva, G.
Title Thermally induced change in the vortex dimensionality of YBa2Cu3O7 single crystals Type Journal Article
Year 1994 Publication Philosophical Magazine Part B Abbreviated Journal Philos. Mag. B
Volume 70 Issue 3 Pages 773 - 786
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Abstract Transport measurements in YBa2Cu3O7 single crystals using a modification of the d.c. flux transformer configuration are reported. We show that, for applied magnetic fields in the crystallographic c direction, the vortex correlation length in this direction is reduced to values smaller than the thickness of the sample. The reduction can be induced either by thermal disorder (linear response) or by flux cutting after the vortices reach a critical velocity (nonlinear response). The results show that, in the transition from a vortex-glass state to a vortex-liquid state, the vortices are effectively three dimensional in character. A two-dimensional regime is induced at higher temperatures well inside the reversibility region.
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Call Number BT @ gnieva @ Serial 456
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Author (up) de la Cruz, F.; López, D.; Righi, E. F.; Nieva, G.
Title Comparative Study of Vortex Correlation in Twinned and Untwinned YBa2Cu3O7 Single Crystals Type Conference Article
Year 1996 Publication Proceedings of the 10th Anniversary Hts Workshop on Physics, Materials and Applications Abbreviated Journal
Volume Issue Pages 395
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Publisher World Scientific Publishing Company Place of Publication Singapore Editor Batlogg, B.
Language Summary Language Original Title
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ISSN ISBN 9810227159 Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ gnieva @ Serial 461
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Author (up) de la Cruz, F.; Pastoriza, H.; López, D.; Goffman, M. F.; Arribére, A.; Nieva, G.
Title Consequences of 3D-2D vortex decoupling on the phase diagram of HTS Type Journal Article
Year 1994 Publication Physica C: Superconductivity Abbreviated Journal Physica C
Volume 235-240 Issue 1 Pages 83-86
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Abstract We discuss the quench of the long range order in the direction parallel and perpendicular to the field, in the mixed state of BSCCO(2212) and YBCO(123) single crystals. The experimental data show that the high temperature vortex phase in both systems is an uncorrelated liquid phase in all directions.
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Call Number BT @ gnieva @ Serial 453
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Author (up) Dolz, M.I.; Shalóm, D.E.; Pastoriza, H.; López, D.O.
Title Anisotropic response of the moving vortex lattice in superconducting Mo(1−x)Gex amorphous films Type Journal Article
Year 2012 Publication Physica C: Superconductivity Abbreviated Journal
Volume 474 Issue Pages 34-37
Keywords Superconductivity; 2D systems; Transverse critical current; Anisotropic behavior
Abstract We have performed magnetic susceptibility measurements in Mo(1−x)Gex amorphous thin films biased with an electrical current using anisotropic coils. We tested the symmetry of the vortex response changing the relative orientation between the bias current and the susceptibility coils. We found a region in the DC current–temperature phase diagram where the dynamical vortex structures behave anisotropically. In this region the shielding capability of the superconducting currents measured by the susceptibility coils is less effective along the direction of vortex motion compared to the transverse direction. This anisotropic response is found in the same region where the peak effect in the critical current is developed. On rising temperature the isotropic behavior is recovered.
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ISSN 0921-4534 ISBN Medium
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Notes Approved no
Call Number BT @ hernan @ Serial 638
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Author (up) López, D.; Nieva, G.; de la Cruz, F.
Title Long range correlations of the vortex structure in YBCO single crystals Type Journal Article
Year 1994 Publication Physica C: Superconductivity Abbreviated Journal Physica C
Volume 235-240 Issue 4 Pages 2575-2576
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Abstract Transport measurements in the mixed state of YBa2Cu3O7 single crystals using the “DC flux transformer” configuration show that the glass-liquid phase transition at the irreversibility line, TI(H), behaves as a three dimensional vortex phase transition. These results together with resistance measurements in the c direction show that the vortex correlation across the sample is destroyed at a temperature Tth(H), higher than TI(H). The sample thickness dependence of Tth(H) suggest that in the real thermodynamic phase transition (infinite sample), the long range correlation in the ab plane as well in the c direction is lost at the single temperature TI(H).
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Call Number BT @ gnieva @ Serial 451
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Author (up) López, D.; Nieva, G.; de la Cruz, F.; Jensen, Henrik Jeldtoft; O’Kane, Dominic
Title Flux cutting in YBa2Cu3O7-δ single crystals: Experiment and phenomenological model Type Journal Article
Year 1994 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 50 Issue Pages 9684
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Abstract We measured the current-induced loss of vortex correlation in YBa2Cu3O7-δ crystals using the pseudo-dc-flux-transformer geometry. We find that the current density Jcut at which the top and bottom voltage drops differ is a linear function of temperature, is independent of pinning, and depends on the thickness of the sample. This thickness dependence strongly suggests that the electrical current flows at the surface of the sample. The observed behavior with temperature, magnetic field, and thickness is described by a phenomenological model.
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Call Number BT @ gnieva @ Serial 445
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Author (up) López, D.; Decca, R.; de la Cruz, F.
Title Topological pinning and flux flow in ceramic superconductors Type Journal Article
Year 1991 Publication Solid State Communications Abbreviated Journal
Volume 79 Issue 11 Pages 959-962
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Abstract The transport current dissipation in the high Tc superconducting ceramic La1.85Sr0.15CuO4−δ shows a sin2 Θ voltage dependence where Θ is the angle between the transport current and the magnetic field. This result and the experimental evidence of an angle independent critical current cannot be explained by the conventional description of flux motion in homogeneous type II superconductors. The results are analyzed in the framework of a granular system where pinning is induced by the topological distribution of current flowing through a multiply connected medium. The dissipation in the superconducting state is found to be due to two additive contributions, one induced by the movement of magnetic flux and the other associated to dissipation in the Josephson junction.
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ISSN 0038-1098 ISBN Medium
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Notes Approved no
Call Number BT @ pedrazp @ Serial 808
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Author (up) López, D.; Jagla, E. A.; Righi, E. F.; Osquiguil, E.; Nieva, G.; Morré, E.; de la Cruz, F.; Balseiro, C. A.
Title Dynamic softening of vortex lines in YBa2Cu3O7−δ single crystals Type Journal Article
Year 1996 Publication Physica C: Superconductivity Abbreviated Journal Physica C
Volume 260 Issue 3-4 Pages 211-216
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Abstract Transport measurements in the mixed state of oxygen-deficient YBa2Cu3O7−δ single crystals using the flux transformer configuration show that the flux liquid changes with increasing anisotropy from strongly correlated to uncorrelated in the field direction. For intermediate coupling, the current inducing loss of vortex correlation has a maximum near the irreversibility temperature. Thus, an effective softening of vortex lines with decreasing temperature is detected. We propose a simple model that accounts for this behavior by including the effects of the pinning potential on the dynamics of vortices.
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Call Number BT @ gnieva @ Serial 454
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Author (up) López, D.; Nieva, G.; de la Cruz, F.
Title In- and out-of-plane vortex correlations in YBa2Cu3O7 Type Journal Article
Year 1994 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 50 Issue Pages 7219
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Call Number BT @ gnieva @ Serial 444
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Author (up) López, D.; Righi, E. F.; Nieva, G.; de la Cruz, F.; Kwok, W. K.; Fendrich, J. A.; Crabtree, G. W.; Paulius, L.
Title Discontinuous Onset of the c-axis Vortex Correlation at the Melting Transition in YBa2Cu3O7 Type Conference Article
Year 1996 Publication Proceedings of the 10th Anniversary Hts Workshop on Physics, Materials and Applications Abbreviated Journal
Volume Issue Pages 411
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Publisher World Scientific Publishing Company Place of Publication Singapore Editor Batlogg, B.
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN 9810227159 Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ gnieva @ Serial 462
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