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Author Correa, V.F.; Nieva, G.; Pastoriza, H.; de la Cruz, F.
Title The true pinning force range in Bi2Sr2CaCu2O8 single crystals at low temperatures Type Journal Article
Year 2004 Publication Physica C Abbreviated Journal
Volume 408-410 Issue Pages 531-532
Keywords
Abstract We study the effective profile of the pinning potential well in Bi$2$Sr$2$CaCu$_2$O8+δ single crystals using transverse ac magnetic susceptibility. The results show that the harmonic approximation for the potential well (linear regime) is valid up to vortex displacements $r\simeqξ$, where ξ, is the coherence length. In spite of this, it is necessary to induce displacements of the vortex structure much larger than ξ to depin it from its potential. This is shown to take place even in the single vortex limit.
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Call Number BT @ hernan @ correa04 Serial (up) 9
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Author Fasano, Y.; de Seta, M.; Menghini, M.; Pastoriza, H.; de la Cruz, F.
Title Imaging the structure of the interface between symmetries interconnected by a discontinuous transition Type Journal Article
Year 2003 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 128 Issue 3-4 Pages 51-55
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Abstract We have been able to observe with single particle resolution the interface between two structural symmetries that cannot be interconnected by a continuous transition. By means of an engineered 2D potential that pins the extremity of vortex strings a square symmetry was imposed at the surface of a 3D vortex solid. Using the Bitter decoration technique and on account of the continuous vortex symmetry, we visualize how the induced structure transforms along the vortex direction before changing into the expected hexagonal structure at a finite distance from the surface.
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Call Number BT @ hernan @ fasano03a Serial (up) 18
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Author Monton, C.; de la Cruz, F.; Guimpel, J.
Title Magnetic state modification induced by superconducting response in ferromagnet/superconductor Nb/Co superlattices Type Journal Article
Year 2008 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 77 Issue 10 Pages
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Abstract Magnetization measurements in superconductor/ferromagnet Nb/Co superlattices show a complex behavior as a function of temperature, applied field, and sample history. Based on a simple model, it is shown that this behavior is due to an interplay between the superconductor magnetization temperature dependence, the ferromagnet magnetization time dependence, and the stray fields of both materials. It is also shown that the magnetic state of the Co layers is modified by the Nb superconducting response, implying that the problem of a superconductor/ferromagnetic heterogeneous sample has to be solved in a self-consistent manner.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
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Notes ISI:000254542700117 Approved no
Call Number BT @ hernan @ Serial (up) 146
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Author Monton, C.; Guimpel, J.; de la Cruz, F.
Title Superconducting behaviour of Nb/Co superlattices Type Journal Article
Year 2007 Publication Applied Surface Science Abbreviated Journal Appl. Surf. Sci.
Volume 254 Issue 1 Pages 375-377
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Abstract We study the superconducting and magnetic behaviour of Nb/Co superlattices, for superconducting Nb layer thickness of 44 nm and Co layer thickness less than 1 nm. In this limit no ferromagnetism is observed for Co. The superlattice behaves as independent superconducting Nb layers. We obtain the penetration depth and superconducting gap of the material, and analyze the results in terms of microscopic models and theories. (C) 2007 Elsevier B.V. All rights reserved.
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ISSN 0169-4332 ISBN Medium
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Notes ISI:000250800100085 Approved no
Call Number BT @ hernan @ Serial (up) 149
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Author Monton, C.; de la Cruz, F.; Guimpel, J.
Title Magnetic behavior of superconductor/ferromagnet superlattices Type Journal Article
Year 2007 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 75 Issue 6 Pages
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Abstract A study of the electromagnetic response of superconductor/ferromagnet Nb/Co superlattices is presented. The dc magnetization is measured as a function of Co layer thickness, applied field H-a, and temperature. For very thin Co layers, no ferromagnetism is detected and the observed response is essentially that of a collection of uncoupled Nb layers. When the Co layer is thick enough for ferromagnetism to be established, prior to the field-cooled magnetization measurements, the Co layers are magnetically saturated in the parallel or antiparallel directions to H-a. In this case, the magnetic response of the otherwise uncoupled Nb layers is found to depend on both H-a and the stray fields.
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Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
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Notes ISI:000244533000075 Approved no
Call Number BT @ hernan @ Serial (up) 151
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Author Ferrari, H.; Valenzuela, S.O.; Bekeris, V.; Guimpel, J.; de la Cruz, F.
Title Short-time magnetization in superconducting thin films Type Journal Article
Year 1998 Publication REVISTA MEXICANA DE FISICA Abbreviated Journal
Volume 44 Issue Pages 193-195
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Abstract We have investigated the magnetization in thin (Y;Gd)Ba2Cu3O7-delta superconducting films in the 100 μs time scale. Magnetic moment was measured with a non-conventional technique that combines the use of a pulsed magnetic field and a synchronized pulsed laser. Both virgin and magnetically cycled samples were examined and results are described within Bean's critical state model.
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Series Volume Series Issue Edition
ISSN 0035-001X ISBN Medium
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Notes ISI:000077675900051 Approved no
Call Number BT @ hernan @ Serial (up) 182
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Author Valenzuela, S.O.; Ferrari, H.; Bekeris, V.; Marconi, M.C.; Guimpel, J.; de la Cruz, F.
Title Nonconventional short-time dc magnetometer for superconducting films Type Journal Article
Year 1998 Publication REVIEW OF SCIENTIFIC INSTRUMENTS Abbreviated Journal
Volume 69 Issue 1 Pages 251-254
Keywords
Abstract A nonconventional technique for the measurement of magnetic relaxation in superconducting films at short times (similar to 10(-5) s) is described. This technique combines the application of a pulsed magnetic field and a synchronized high-energy pulsed laser. Remanent magnetic relaxation in (Y;Gd)Ba2Cu3O7-delta thin films is reported over five decades time at reduced temperatures above 0.8. (C) 1998 American Institute of Physics.
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Series Volume Series Issue Edition
ISSN 0034-6748 ISBN Medium
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Notes ISI:000071578800041 Approved no
Call Number BT @ hernan @ Serial (up) 185
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Author Guimpel, J.; de la Cruz, M.E.; de la Cruz, F.; Fink, H.J.; Laborde, O.; Villegier, J.C.
Title Size dependence of the Superconducting critical temperature and fields of Nb/Al multilayers Type Journal Article
Year 1986 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 63 Issue 1-2 Pages 151-165
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Abstract The critical temperatureT cof Nb/Al multilayers decreases as the total sample thicknessd Tis decreased while the thickness of each Nb and Al layer is kept constant. To understand this behavior, models based on the proximity effect and on weak two-dimensional (2D) localization are employed. The latter uses a characteristic length, the thermal diffusion length, in relation tod Tto obtain 2D behavior and leads to a reasonable explanation ofT c(d T). It is also found that the slope atT c(d T) of the critical magnetic field perpendicular to the layers is independent ofd Twhen the Nb and Al layer thicknesses are kept constant. The angular dependence of the critical field is also measured.
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ISSN 0022-2291 ISBN Medium
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Notes ISI:A1986C112200008 Approved no
Call Number BT @ hernan @ Serial (up) 193
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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
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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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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Medium
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Notes ISI:000259188700052 Approved no
Call Number BT @ hernan @ Serial (up) 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
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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 Series Issue Edition
ISSN 0921-4534 ISBN Medium
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Notes ISI:000249870600060 Approved no
Call Number BT @ hernan @ Serial (up) 198
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