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Author (up) Bahrs, S.; Goni, A.R.; Maiorov, B.; Nieva, G.; Fainstein, A.; Thomsen, C.
Title Raman-study of photoinduced chain-oxygen ordering in RBa2Cu3O7-delta Type Journal Article
Year 2003 Publication IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Abbreviated Journal
Volume 13 Issue 2 Pages 3192-3195
Keywords
Abstract We investigated Raman-forbidden signals in RBa2Cu3O7-delta with R = Y or Pr, which lose intensity under illumination at low temperatures. These defect-induced,peaks are only visible in oxygen-deficient material and for light polarized parallel to the copper-oxygen chains along the material's b-axis. In a first, two-laser based experiment we established that the bleaching effect of the light is polarization dependent as well. From this and other known properties we conclude that the signal is connected to the copper-oxygen chains, reflecting their state of disorder, and is thus closely related to aging and to the persistent photoconductivity effect in the material. In a second set of experiments we followed the temperature dependence of the Raman spectra and the intensity decrease.
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ISSN 1051-8223 ISBN Medium
Area Expedition Conference
Notes ISI:000184242400193 Approved no
Call Number BT @ hernan @ Serial 209
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Author (up) Custers, J.; Cichorek, T.; Gegenwart, P.; Caroca-Canales, N.; Stockert, O.; Geibel, C.; Steglich, F.; Pedrazzini, P.; Sereni, J.G.
Title Non-Fermi liquid effects close to a QCP in CeIn3-xSnx Type Journal Article
Year 2003 Publication ACTA PHYSICA POLONICA B Abbreviated Journal
Volume 34 Issue 2 Pages 379-382
Keywords
Abstract Resistivity and specific heat measurements at low temperatures on CeIn3-xSnx samples with concentrations x = 0.6, 0.65 and 0.7 demonstrate that with increasing Sn-alloying, the antiferromagnetic ordering temperature decreases continuously down to T = 0 K and disappears at a quantum critical point. We observe non-Fermi liquid (NFL) behavior in the resistivity and the specific heat, however the temperature dependencies are different from the predictions for a spin density wave (SDW) scenario. The resistivity at the critical point shows e.g., a linear temperature dependence, as expected for two dimensional fluctuations, which however can be excluded in the cubic structure of CeIn3-xSnx.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0587-4254 ISBN Medium
Area Expedition Conference
Notes ISI:000181544200015 Approved no
Call Number BT @ hernan @ Serial 68
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Author (up) 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
Keywords
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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Notes Approved no
Call Number BT @ hernan @ fasano03a Serial 18
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Author (up) Fasano, Yanina
Title Observación microscópica de transformaciones estructurales en la materia de vórtices : desorden, elasticidad, dimensionalidad y dinámica de nucleación y crecimiento Type Book Whole
Year 2003 Publication Abbreviated Journal
Volume Issue Pages
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Abstract
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Corporate Author Thesis Ph.D. thesis
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Notes Approved no
Call Number BT @ hernan @ Serial 332
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Author (up) Haberkorn, N.; Guimpel, J.; Steren, L.B.; Campillo, G.; Saldarriaga, W.; Gomez, M.E.
Title Structure of high-T-c/manganite perovskite superlattices Type Journal Article
Year 2003 Publication JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 94 Issue 5 Pages 3011-3014
Keywords
Abstract We study the crystalline and interface structure of RBa2Cu3O7/La(1-x)A(x)MnO(3) superlattices (R=Y, Gd; A=Ca, Sr) grown on mismatched MgO substrates by means of nondestructive x-ray diffraction. The diffraction patterns are adjusted to a model of the structure which includes interface roughness and interdiffusion. Our results show that these disorder mechanisms cannot be neglected and should be taken into account to understand the physical properties of these superlattice. (C) 2003 American Institute of Physics.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979 ISBN Medium
Area Expedition Conference
Notes ISI:000184844200032 Approved no
Call Number BT @ hernan @ Serial 167
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Author (up) Maiorov, Boris A.
Title Transición de fase y dinámica de vórtices en YBa2Cu3O7-δ Type Book Whole
Year 2003 Publication Abbreviated Journal
Volume Issue Pages
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Address Instituto Balseiro
Corporate Author Thesis Ph.D. thesis
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Notes Approved no
Call Number BT @ hernan @ Serial 333
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Author (up) Menghini, Mariela A.
Title Transición de fase líquido-sólido de vórtices de primer orden con y sin cambio de simetría Type Book Whole
Year 2003 Publication Abbreviated Journal
Volume Issue Pages
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Abstract
Address
Corporate Author Thesis Ph.D. thesis
Publisher Place of Publication Editor
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Notes Approved no
Call Number BT @ hernan @ Serial 334
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Author (up) Pedrazzini, P.
Title Estudio comparativo de inestabilidades magneticas en compuestos de cerio Type Book Whole
Year 2003 Publication Abbreviated Journal
Volume Issue Pages 116
Keywords
Abstract La variedad de nuevos estados y fenómenos físicos descubiertos en compuestos intermetálicos que contienen tierras raras o actínidos ha motivado, durante las últimas cuatro décadas, el estudio sostenido de sus diagramas de fases magnéticas. El interés actual se centra en el estudio de la región del diagrama de fases en la que se desestabiliza el orden magnético en sistemas en base a cerio, yterbio y uranio. En dicha región se han detectado, por ejemplo, superconductividad no convencional y el comportamiento denominado “non-Fermi liquid” (NFL), caracterizado por dependencias anómalas de las propiedades térmicas, magnéticas y de transporte a muy bajas temperaturas.Un esquema sencillo, el denominado “diagrama de Doniach”, ha guiado la interpretación de la desestabilización del orden magnético de los sistemas antes mencionados. Sin embargo, la mayoría de los sistemas estudiados no pueden ser descriptos por dicho esquema, lo que ha motivado el desarrollo de una clasificación fenomenológica de los diagramas de fases que ha sido aplicada fundamentalmente a compuestos en base a cerio. Dicha clasificación define tres tipos de diagramas de fase que pueden distinguirse a través de la forma en que el orden magnético es suprimido al variar un parámetro de control (por ejemplo, concentración o presión), acercándose a su valor crítico. Dentro de este contexto, presentamos el estudio de la supresión del orden antiferromagnético de los compuestos intermetálicos CeIn3, CeRh2Si2 y CePd2Al3 cuando se alean los ligantes del Ce. Los sistemas resultantes, CeIn3−xSnx, Ce(CuxRh1−x)2Si2 y CePd2−xNixAl 3, presentan diferentes estructuras cristalinas y los efectos producidos por la aleación son distintos en cada uno de los casos. Sus diagramas de fases magnéticas son analizados y comparados con la clasificación fenomenológica antes mencionada, por lo que se investiga en más detalle la región en la que se produce la inestabilidad magnética, en las cercanías de las respectivas concentraciones críticas. A partir de nuestros resultados y de lo reportado en la literatura, discutimos la mencionada clasificación fenomenológica. Los principales resultados de este trabajo están asociados al diagrama de fases complejo del sistema cúbico CeIn3−xSnx, en el que la temperatura de orden antiferromagnético (AF), TN(x), puede ser detectada en más de un orden y medio de magnitud en temperatura. Alrededor de la concentración crítica xc #approx =# 0,65 en que TN #-># 0 se observa comportamiento del tipo NFL. En el caso del sistema Ce(CuxRh1−x)2Si2, la relevancia de este estudio se basa en la comparación con el sistema isoestructural Ce(PdzRh1−z)2Si2, que permite descartar un rol fundamental de la anisotropía en la supresión del orden magnético AF del compuesto CeRh2Si2 (anómalo, pues TN = 36 K). Finalmente, el estudio del CePd2−xNixAl_3 revela un diagrama de fases complejo que puede estar asociado al desorden producido al alear, y en el que también se observa comportamiento del tipo NFL. El estudio conjunto de los sistemas mencionados permite postular escenarios en los que variables adicionales, que no son tenidas en cuenta por el esquema de Doniach, conducen a los distintos comportamientos observados.
Address Instituto Balseiro – CNEA y UNCuyo, 8400 S.C. de Bariloche
Corporate Author Thesis Ph.D. thesis
Publisher Place of Publication Editor
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Notes Approved no
Call Number BT @ hernan @ Serial 335
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Author (up) Pedrazzini, P.; Berisso, M.G.; Sereni, J.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C.
Title Complex magnetic phase diagram near the quantum critical point in CeIn3-xSnx Type Journal Article
Year 2003 Publication ACTA PHYSICA POLONICA B Abbreviated Journal
Volume 34 Issue 2 Pages 363-366
Keywords
Abstract A recent reinvestigation of the alloy system CeIn3-xSnx between the antiferromagnetic (AF) Kondo-lattice CeIn3 and the intermediate valent CeSn3 has shown that the AF order disappears at a quantum critical point (QCP) at x(c) approximate to 0.65. Preliminary evidences for a first order transition below T-N at x < x(c), indicating a complex magnetic phase diagram, have motivated the present detailed investigation of specific heat and resistivity on fine tuned samples in the 0.25 less than or equal to x less than or equal to x(c) range. These results confirm the first order transition at T-I < T-N in a reduced concentration range (0.25 < x < 0.47) and suggest that the phase boundary T-I (x) merge with the T-N(x) near x approximate to 0.37, leading to a tetracritical point. A similar first order transition was previously observed in the CeCu2(Si,Ge)(2) system at low Ge-concentration. Since in this alloy the first order transition also appears in the vicinity of a QCP, the question arises concerning how general this property is at AF critical points in Ce-based alloy systems.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 0587-4254 ISBN Medium
Area Expedition Conference
Notes ISI:000181544200011 Approved no
Call Number BT @ hernan @ Serial 292
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Author (up) Shalóm, D. E.; Pastoriza, H.
Title Experimental evidence for anisotropic response of a driven vortex lattice Type Journal Article
Year 2003 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 126 Issue 7 Pages 379-383
Keywords
Abstract We present kinetic inductance measurements in current driven Josephson junction arrays. Measurements performed with circular coils indicate that this technique is very sensitive to the vortex mobility. Results obtained with anisotropic detection coils provide experimental evidence for the anisotropic response of a driven vortex lattice. Anisotropic behavior is obtained when rising the temperature or the mean vortex velocity as indicated by the loss of the superconducting shielding capability, first in the direction of vortex motion and then in the perpendicular direction.
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Notes Approved no
Call Number BT @ hernan @ shalom03 Serial 42
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