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Autor León Yebra, Carlos |
Documentos disponibles escritos por este autor (82)
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Experimental frequency-dependent conductivity relaxation spectra of a number of molten, glassy, and crystalline ionic conductors that show both the presence of the near constant loss (NCL) and the cooperative ion hopping contribution are analyze[...]![]()
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Díaz Guillén, M. R. ; Moreno, K. J. ; Díaz Guillén, J. A. ; Fuentes, A .F. ; Naval, K. L. Ngai ; Garcia Barriocanal, Javier ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | American Physical Society | 2008-09In this work we evaluate the effect of cation size on the dc activation energy needed for oxygen ion migration, E_(dc), in highly disordered pyrochlore-type ionic conductors A_(2)B_(2)O_(7). Twenty six compositions with the general formula, Ln_([...]![]()
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Salafranca, Juan ; Rincón, Julián ; Tornos Castillo, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; Dagotto, Elbio ; Pennycook, Stephen J. ; Varela del Arco, María | American Physical Society | 2014-05-14Here we study the electronic properties of cuprate-manganite interfaces. By means of atomic resolution electron microscopy and spectroscopy, we produce a subnanometer scale map of the transition metal oxidation state profile across the interface[...]![]()
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Peña, V. ; Rivera Calzada, Alberto Carlos ; Garcia Barriocanal, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; García González, E. ; González Calbet, J. M. | Sociedad Española de Cerámica y Vidrio | 2004-01Presentamos medidas de la conductividad eléctrica del sistema BIFEVOX Bi_(4)V_(2-x)Fe_(x)O_(11-y)(0?x?0.9;0?y?1), en el que se realiza la sustitución de iones V (IV) por Fe (III) de forma sistemática. La conductividad muestra un comportamiento p[...]![]()
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Hernández Martín, David ; Gallego Toledo, Fernando ; Tornos Castillo, Javier ; Rouco Gómez, Víctor ; Beltrán Finez, Juan Ignacio ; Munuera, C. ; Sánchez Manzano, David ; Cabero Piris, Mariona ; Cuéllar Jiménez, Fabián Andrés ; Arias Serna, Diego ; Sánchez Santolino, Gabriel ; Mompean, F. J. ; Gárcia Hernández, M. ; Rivera Calzada, Alberto Carlos ; Pennycook, S. J. ; Varela del Arco, María ; Muñoz, M. C. ; Sefrioui, Zouhair ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2020-12-30The persistence of ferroelectricity in ultrathin layers relies critically on screening or compensation of polarization charges which otherwise destabilize the ferroelectric state. At surfaces, charged defects play a crucial role in the screening[...]![]()
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Moreno, K. J. ; Mendoza-Suárez, G. ; Fuentes, A. F. ; Garcia Barriocanal, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2005-04-22We report on dispersive conductivity measurements in the oxygen ion conductor Gd_(2)(Ti_(2?y)Zr_(y))O_(7). Increasing Zr content leads to higher concentration of oxygen vacancies and results in higher activation energies for long-range ion trans[...]![]()
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León Yebra, Carlos ; Lucía Mulas, María Luisa ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 1997-01-01A study of the effect of correlated ion motion on the electrical conductivity relaxation in single-crystalline yttria-stabilized zirconia is presented. Complex admittance in the radio frequency range show power-law dependencies in the real part[...]![]()
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León Yebra, Carlos ; Ngai, K. L. ; Rivera Calzada, Alberto Carlos | American Physical Society | 2004-04-16For ionic conductivity relaxation in ionically conducting materials we predict in the framework of the coupling model that the magnitude of the ubiquitous near constant loss correlates with the activation energy E_(a) for independent ion hopping[...]![]()
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Peña, V. ; Sefrioui, Zouhair ; Arias Serna, Diego ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; Varela del Arco, María ; Pennycook, S. J. ; Martínez, J. L. | American Physical Society | 2004-06-08Here we examine the ferromagnetic/superconducting proximity effect in half-metallic ferromagnetic La_(0.7)Ca_(0.3)MnO_(3) and high-T_(c) superconducting YBa_(2)Cu_(3)O_(7) artificial structures. We have found experimental evidence for the coupli[...]![]()
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Rivera Calzada, Alberto Carlos ; León Yebra, Carlos ; Sanz, J. ; Santamaría Sánchez-Barriga, Jacobo ; Moynihan, C. T. ; Ngai, K. L. | American Physical Society | 2002-06-10Electrical conductivity measurements of the fast ionic conductor Li_(0.18)La_(0.61)TiO_(3) have been conducted at temperatures ranging from 8 to 300 K and frequencies between 20 Hz and 5 MHz. A detailed analysis of the ac conductivity shows the [...]![]()
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Sefrioui, Zouhair ; Arias Serna, Diego ; Varela del Arco, María ; Villegas, J. E. ; López de la Torre, M. A. ; León Yebra, Carlos ; Loos, G. D. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 1999-12-01Current-voltage (I-V) characteristics were used to investigate the response of the vortex-glass (VG) phase transition in high-quality epitaxial YBa_(2)Cu_(3)O_(7-?) films in magnetic fields up to 7 T. We show that varying the oxygen content, the[...]![]()
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Díaz Guillén, M. R. ; Díaz Guillén, J. A. ; Fuentes, A. F. ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | American Physical Society | 2010-11-18We report on ac conductivity measurements of oxide ion conductors with composition Gd_(2)(Zr_(y)Ti_(1?y)_(2)O_(7), at temperatures between 170 and 500 K and in the frequency range 1 Hz–3MHz, and show that a crossover from a sublinear power law t[...]![]()
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Varela del Arco, María ; Arias Serna, Diego ; Sefrioui, Zouhair ; León Yebra, Carlos ; Ballesteros, C. ; Pennycook, S. J. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2002-10-01We report the effects of epitaxial strain and deoxygenation on high quality [YBa_(2)Cu_(3)O_(7-x)(YBCO)_(N) /PrBa_(2)Cu_(3)O_(7)(PBCO)_(5)]_(1000 Å) superlattices, with 1![]()
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Varela del Arco, María ; Grogger, W. ; Arias Serna, Diego ; Sefrioui, Zouhair ; León Yebra, Carlos ; Ballesteros, C. ; Frishnan, K.M. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2001-05-28Charge neutrality and stoichiometry impose severe restrictions on the mechanisms of epitaxial growth of complex oxides. The fundamental question arises of what is the minimum growth unit when sample thickness is reduced beyond the size of the un[...]![]()
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Nemes, Norbert Marcel ; Rocci, Mirko ; Sefrioui, Zouhair ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2010-03-01We report on the magnetic anisotropy controlled modulation of the superconductivity in La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7??)/La_(0.7)Ca_(0.3)MnO_(3) ferromagnet/superconductor/ferromagnet hybrids with biaxial easy axes. The magnetoresista[...]![]()
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Garcia Barriocanal, Javier ; Pérez Muñoz, Ana Mª ; Sefrioui, Zouhair ; Arias Serna, Diego ; Varela del Arco, María ; León Yebra, Carlos ; Pennycook, Stephen J. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2013-06-11We examine the effect of interface disorder in suppressing superconductivity in coherently grown ultrathin YBa_(2)Cu_(3)O_(7) (YBCO) layers on SrTiO_(3) (STO) in YBCO/STO superlattices. The termination plane of the STO is TiO_(2) and the CuO cha[...]![]()
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Nemes, Norbert Marcel ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2012-05-18We examine the anomalous inverse spin switch behavior in La_(0.7)Ca_(0.3)MnO_(3)(LCMO)=YBa_(2)Cu_(3)O_(7-?(YBCO)/LCMO trilayers by combined transport studies and polarized neutron reflectometry. Measuring magnetization profiles and magnetoresist[...]![]()
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Varela del Arco, María ; Grogger, W. ; Arias Serna, Diego ; Sefrioui, Zouhair ; León Yebra, Carlos ; Vázquez, L. ; Ballesteros, C. ; Krishnan, K.M. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2002-11-01We report on the growth mechanism of YBa_(2)Cu_(3)O_(7-x). Our study is based on an analysis of ultrathin YBa_(2)Cu_(3)O_(7-x) (YBCO) layers in c-axis-oriented YBa_(2)Cu_(3)O_(7-x)/PrBa_(2)Cu_(3)O_(7)superlattices. We have found that the release[...]![]()
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Bruno, F. Y. ; Garcia Barriocanal, Javier ; Torija, M. ; Rivera Calzada, Alberto Carlos ; Sefrioui, Zouhair ; Leighton, C. ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Institute of Physics | 2008-02-25Electrical transport properties of heteroepitaxial p-n junctions made of La_(0.8)Sr_(0.2)CoO_(3) and SrTi_(0.99)Nb_(0.01)O_(3) were studied. Junctions display highly rectifying current-voltage characteristics over a wide temperature range (20–30[...]![]()
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Frechero, M. A. ; Rocci, Mirko ; Schmidt, Rainer ; Díaz Guillén, M. R. ; Durá, O. J. ; Rivera Calzada, Alberto Carlos ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | Sociedad Española de Cerámica y Vidrio | 2012-01Here we show impedance spectroscopy measurements on a bicrystal of the ionically conducting yttria stabilized zirconia (YSZ). By using micrometer sized electrodes it is possible to measure ionic transport perpendicular to a single grain boundary[...]![]()
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León Yebra, Carlos ; Lucía Mulas, María Luisa ; Santamaría Sánchez-Barriga, Jacobo ; París, M. A. ; Sanz, J. ; Várez, A. | American Physical Society | 1996-07-01Lithium ionic conductivity of Li_(0.5)La_(0.5)TiO_(3) has been studied using nuclear magnetic resonance (NMR) and admittance spectroscopy (AS) techniques. Spin-lattice relaxation and electrical conductivity relaxation are well described in terms[...]![]()
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Rivera Calzada, Alberto Carlos ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | American Institute of Physics | 2001-01-29We report on complex admittance measurements on ZrO_(2):Y_(2)O_(3) (YSZ) thin films in the parallel plate geometry. Highly textured YSZ thin films, grown by rf sputtering, allow measuring complex admittance free of the effect of charge blocking [...]![]()
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López de la Torre, M. A. ; Sefrioui, Zouhair ; Arias Serna, Diego ; Varela del Arco, María ; Villegas, J. E. ; Ballesteros, C. ; León Yebra, Carlos | American Physical Society | 2001-01-05We report on the effect of light ion irradiation on the low-temperature electrical resistivity of ferromagnetic SrRuO_(3) thin films. Fresh samples displayed a ferromagnetic transition at T_(c)? 160 K, good metallic behavior (?(300 K)~400??cm, d[...]