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Author Bridoux, G.; Nieva, G.; de la Cruz, F.
Title Phase-coherence effects in vortex transport entropy Type Journal Article
Year 2008 Publication PHYSICAL REVIEW LETTERS Abbreviated Journal
Volume 101 Issue 11 Pages 117002
Keywords
Abstract Nernst and electrical resistivity measurements in superconducting YBa2Cu3O7-delta and Bi2Sr2CaCu2O8+delta with and without columnar defects show a distinctive thermodynamics of the respective liquid vortex matter. At a field-dependent high temperature region in the H-T phase diagram, the Nernst signal is independent of structural defects in both materials. At lower temperatures, in YBa2Cu3O7-delta, defects contribute only to the vortex mobility, and the transport entropy is that of a system of vortex lines. The transition to lower temperatures in Bi2Sr2CaCu2O8+delta has a different origin; the maximum in the Nernst signal when decreasing temperature is not associated with transport properties but with the entropy behavior of pancake vortices in the presence of structural defects.
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ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes ISI:000259188700052 Approved no
Call Number BT @ hernan @ Serial 195
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Author Bridoux, G.; Pedrazzini, P.; de la Cruz, F.; Nieva, G.
Title Angular field dependence of the Nernst effect in Bi2Sr2CaCu2O8+delta Type Journal Article
Year 2007 Publication PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Abbreviated Journal
Volume 460 Issue Pages 841-842
Keywords
Abstract The anomalous Nernst effect in hole-doped cuprates has been interpreted in terms of the existence of a superconducting order parameter well above the transition temperature, T-c(H). In order to improve the understanding of this problem, we have measured the angular field dependence of the Nernst signal in Bi2Sr2CaCu2O8+delta single crystals. The experiment was done tilting the magnetic field with respect to the direction of the temperature gradient, above and below T,(H), with applied fields up to 16 T. We have found that all the curves are scaled on one curve against the reduced field Hcos theta at a fixed temperature. (c) 2007 Elsevier B.V. All rights reserved.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 0921-4534 ISBN Medium
Area Expedition Conference
Notes ISI:000249870600060 Approved no
Call Number BT @ hernan @ Serial 198
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Author Grigera, S.A.; Grigera, T.S.; Righi, E.F.; Nieva, G.; de la Cruz, F.
Title Flux-cutting in YBa2Cu3O7-delta revisited Type Journal Article
Year 2002 Publication PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Abbreviated Journal
Volume 371 Issue 3 Pages 237-242
Keywords
Abstract In this paper we present an analysis of the response of the vortices in YBa2Cu3O7-delta to different configurations of applied driving forces. The use of inhomogeneous current allows us to induce vortex cutting. We determine the maximum current injected in different electrical contact distributions which preserves vortex integrity, and we show that vortex cutting cannot be explained by a single vortex picture. (C) 2001 Elsevier Science B.V. All rights reserved.
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ISSN 0921-4534 ISBN Medium
Area Expedition Conference
Notes ISI:000176131500007 Approved no
Call Number BT @ hernan @ Serial 212
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Author Correa, V.F.; Nieva, G.; de la Cruz, F.
Title Vortex softening: Origin of the second peak effect in Bi2Sr2CaCu2O8+delta Type Journal Article
Year 2001 Publication PHYSICAL REVIEW LETTERS Abbreviated Journal
Volume 87 Issue 5 Pages 057003
Keywords
Abstract Magnetic hysteresis and transverse ac permeability measurements in Bi2Sr2CaCu2O8+delta allow a comparative analysis of the critical current with the elastic response of vortex structures, in equilibrium with their pinning potential, in the field and temperature region where the second peak is detected. This study provides strong evidence that the second peak has its origin in changes of the elastic equilibrium properties of the vortex structures.
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ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes ISI:000170212200049 Approved no
Call Number BT @ hernan @ Serial 215
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Author Correa, V.F.; Herbsommer, J.A.; Kaul, E.E.; de la Cruz, F.; Nieva, G.
Title Order-disorder transition and the zero-dimensional vortex pinning regime in Bi2Sr2CaCu2O8+delta Type Journal Article
Year 2001 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 63 Issue 9 Pages 092502
Keywords
Abstract We make a comparative study between the ab plane's dc critical current and the ac transverse magnetic permeability μ(perpendicular to) in the Campbell limit for optimally doped and overdoped Bi2Sr2CaCu2O8+delta samples. We focus attention on the low-temperature region [T/T-c(0) < 0.25], where the transition to the zero-dimensional Larkin limit is detected by the critical current as well as by a rapid change of the Labusch parameter with temperature. The order-disorder transition, characterized by the second peak in magnetization, disappears in the presence of this zero-dimensional pinning regime.
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Series Volume (down) Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:000167312000016 Approved no
Call Number BT @ hernan @ Serial 218
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Author Fasano, Y.; Menghini, M.; de la Cruz, F.; Nieva, G.
Title Weak interaction and matching conditions for replicas of vortex lattices Type Journal Article
Year 2000 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 62 Issue 22 Pages 15183-15189
Keywords
Abstract We present experiments demonstrating the conditions under which weak interaction between replicas of vortex structures break their translational and rotational symmetry. The Fe clumps introduced by Bitter decorations of vortex structures are used to induce an extremely weak interaction fur subsequent vortex structures in low and high temperature superconducting crystals. The matching between the Fe pattern acid the vortex configuration require the structure to be prepared under quite stringent conditions: The field creating the structure has to be the same in magnitude although it can differ in orientation from that used for the preparation of the Fe pattern. The interaction between vortex replicas as represented by the Fe clumps of Bitter decorations makes it possible to differentiate the vortex nucleation and propagation mechanisms in low and high temperature superconductors.
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ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:000165883800075 Approved no
Call Number BT @ hernan @ Serial 219
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Author Correa, V.F.; Herbsommer, J.A.; Kaul, E.E.; de la Cruz, F.; Nieva, G.
Title Onset of the 0-dimensional vortex pinning behavior in the optimally doped and overdoped Bi2Sr2CaCu2O8+delta system Type Journal Article
Year 2000 Publication PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Abbreviated Journal
Volume 341 Issue Pages 1285-1286
Keywords
Abstract We report results of transverse AC magnetic permeability in the linear regime and DC magnetization loops for optimally doped and oxygen overdoped samples of Bi2Sr2CaCu2O8+delta The data cover the low temperature (T < 25K) and low held (H-a < 1000 Oe) region of the magnetic (H-a-T) phase diagram. In optimally doped as well as in overdoped samples a crossover to a O-dimensional pinning regime (Larkin length, L-C(C), shorter than the inter-plane CuO2 distance) is observed at a characteristic temperature Too for all investigated fields. The order-disorder transition, identified by the second peak in magnetization and a non monotonous field dependence of the AC penetration depth, is quenched below T-0D.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 0921-4534 ISBN Medium
Area Expedition Conference
Notes ISI:000165855700242 Approved no
Call Number BT @ hernan @ Serial 221
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Author Grigera, S.A.; Morre, E.; Osquiguil, E.; Nieva, G.; de la Cruz, F.
Title Two-step liquid-solid vortex transition with the field along the ab planes in YBa2Cu3O7-delta crystals Type Journal Article
Year 1999 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 59 Issue 17 Pages 11201-11204
Keywords
Abstract Resistivity measurements for different Lorentz force configurations and the detection of the longitudinal vortex velocity correlation length, with the magnetic field applied parallel to the ab planes, in the mixed state of clean and twinned YBa2Cu3O7-delta single crystals,' support the existence of a vortex-smectic phase when the vortices interact with an attractive periodic potential. The transition from the vortex-liquid to the vortex-solid state is shown to be achieved in two steps, a continuous transition from a liquid to a possible smectic phase and another continuous one from the smectic phase to a solid. [S0163-1829(99)09413-8].
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:000084631900027 Approved no
Call Number BT @ hernan @ Serial 231
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Author Grigera, S.A.; Morre, E.; Osquiguil, E.; Balseiro, C.; Nieva, G.; de la Cruz, F.
Title Bose-glass phase in twinned YBa2Cu3O7-delta Type Journal Article
Year 1998 Publication PHYSICAL REVIEW LETTERS Abbreviated Journal
Volume 81 Issue 11 Pages 2348-2351
Keywords
Abstract Using an extensive scaling analysis of the transport properties in twinned YBa2Cu3O7-delta crystals we have experimentally found the predicted change in the universality class of the Bose-glass to liquid transition when the magnetic field is applied at small angles away from the direction of the correlated defects. The new dynamical critical exponent is s' = 1.1 +/- 0.3.
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Language Summary Language Original Title
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Series Volume (down) Series Issue Edition
ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes ISI:000075897300042 Approved no
Call Number BT @ hernan @ Serial 235
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Author Grigera, S.A.; Morré, E.; Osquiguil, E.; Nieva, G.; De la Cruz, F.
Title Nonlocal transport properties and size effects in heavily twinned YBa2Cu3O7-delta single crystals Type Journal Article
Year 1998 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 107 Issue 7 Pages 335-339
Keywords
Abstract We demonstrate experimentally that when the vortex correlation length in the liquid state becomes of the order of the sample thickness, size effects dominate the transport properties of the macroscopic vortex structures, implying a nonlocal response in the transformer experiments.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 0038-1098 ISBN Medium
Area Expedition Conference
Notes ISI:000074907100004 Approved no
Call Number BT @ hernan @ Serial 237
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