Flux-creep dissipation in epitaxial YBa 2 Cu 3 <mml:math…
1991; American Physical Society; Volume: 43; Issue: 4 Linguagem: Inglês
10.1103/physrevb.43.2962
ISSN1095-3795
AutoresJinhee Kim, Ho-Kyun Lee, Jinwook Chung, Hyun Joon Shin, Hu Jong Lee, Ja Kang Ku,
Tópico(s)Magnetic and transport properties of perovskites and related materials
ResumoWe have investigated the dissipation characteristics in the mixed state of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ film, grown epitaxially on the ${\mathrm{SrTiO}}_{3}$(100) substrate, in terms of external transport current as well as magnetic field applied parallel to the c axis of the film. The dissipation fits well the thermally activated flux creep model, R=${\mathit{R}}_{0}$ exp(-U/${\mathit{k}}_{\mathit{B}}$T), where U is a function of electrical current, magnetic field, and temperature. In the range of current density \ensuremath{\sim}20--4000 A/${\mathrm{cm}}^{2}$, the current dependence of the activation energy U scales with ln(I/${\mathit{I}}_{0}$), as observed recently by Zeldov et al. U shows a power-law dependence on magnetic field as ${\mathit{H}}^{\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\beta}}}$ with \ensuremath{\beta}=0.73\ifmmode\pm\else\textpm\fi{}0.002. We obtain the resistance prefactor ${\mathit{R}}_{0}$ proportional to the applied magnetic field, provided the Ginzburg-Landau-type magnetic-field suppression of the mean-field transition temperature ${\mathit{T}}_{\mathit{c}0}$ is taken into account. In addition, we present the magnetoresistance at various temperatures below ${\mathit{T}}_{\mathit{c}0}$, in good accordance with the flux-creep model.
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