| Records |
| 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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BT @ hernan @ fasano03a |
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18 |
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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 |
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| Volume |
408-410 |
Issue |
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Pages |
531-532 |
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| 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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no |
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BT @ hernan @ correa04 |
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9 |
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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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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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0169-4332 |
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ISI:000250800100085 |
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no |
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BT @ hernan @ |
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149 |
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Monton, C.; de la Cruz, F.; Guimpel, J. |
| Title |
Magnetic behavior of superconductor/ferromagnet superlattices |
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Journal Article |
| Year |
2007 |
Publication |
PHYSICAL REVIEW B |
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75 |
Issue |
6 |
Pages |
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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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1098-0121 |
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ISI:000244533000075 |
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no |
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BT @ hernan @ |
Serial |
151 |
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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 |
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Journal Article |
| Year |
2007 |
Publication |
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS |
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| Volume |
460 |
Issue |
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Pages |
841-842 |
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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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0921-4534 |
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ISI:000249870600060 |
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no |
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BT @ hernan @ |
Serial |
198 |
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| Author |
Guimpel, J.; Monton, C.; Haberkorn, N.; de la Cruz, F. |
| Title |
Magnetic behaviour of superconductor/ferromagnet metallic and perovskite based superlattices |
Type |
Journal Article |
| Year |
2007 |
Publication |
physica status solidi (c) |
Abbreviated Journal |
Phys. Status Solidi (c) |
| Volume |
4 |
Issue |
11 |
Pages |
4174-4180 |
| Keywords |
74.45.+c; 74.78.Fk; 75.70.Cn |
| Abstract |
We present a study of the magnetic behaviour of superconducting/ferromagnetic superlattices, both for metallic and perovskite based systems. In the first case we find that the response is determined by the ferromagnetic layer regime. If these layers are very thin, no ferromagnetism is observed, but the superconducting layers are decoupled, and the superlattice behaves as a stack of independent superconducting films. For thicker ferromagnetic films, ferromagnetism is established and the effective field resulting from the superposition of stray and applied fields dominates the superconducting response of the superlattice. For the perovskite based superlattices, the physical properties are more affected by interface disorder. In this case we have found that the behaviour can be interpeted as charge carrier transfer between both materials, inducing a change in the magnetic character of the manganite. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
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WILEY-VCH Verlag |
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1610-1642 |
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no |
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BT @ jguimpel @ |
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620 |
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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 |
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77 |
Issue |
10 |
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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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1098-0121 |
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ISI:000254542700117 |
Approved |
no |
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BT @ hernan @ |
Serial |
146 |
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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 |
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| Volume |
101 |
Issue |
11 |
Pages |
117002 |
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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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0031-9007 |
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ISI:000259188700052 |
Approved |
no |
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BT @ hernan @ |
Serial |
195 |
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