Fluctuation-induced in-plane conductivity, magnetoconductivity, and diamagnetism of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals in weak magnetic fields
- Laboratorio de Fisica de Materiales, Departamento de Fisica de la Materia Condensada, Universidad de Santiago de Compostela, 15706 Santiago de Compostela (Spain)
We report detailed experimental results on the fluctuation-induced in-plane conductivity {Delta}{sigma}{sub {ital ab}}, magnetoconductivity {Delta}{tilde {sigma}}{sub {ital ab}}, and diamagnetism {Delta}{chi}{sub {ital ab}}, of high-quality Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals. The data were obtained with magnetic fields {ital H} applied perpendicularly to the superconducting (CuO{sub 2}) planes and up to {mu}{sub 0}{ital H}=5 T, which not too close to the transition [for reduced temperatures {var_epsilon}{equivalent_to}({ital T}{minus}{ital T}{sub {ital C}0})/{ital T}{sub {ital C}0}{approx_gt}10{sup {minus}2}] may be considered in the weak magnetic field limit. In the mean field region (MFR) above the transition, these data are analyzed in terms of thermal fluctuations of the superconducting order parameter amplitude (OPF), on the grounds of the existing theoretical approaches for layered superconductors that take into account the presence of two superconducting layers in the layer periodicity length, {ital s}, which for these compounds is equal to one-half the crystallographic unit-cell length in the {ital c} direction. These results show that, due to its strong {var_epsilon} dependence, {Delta}{tilde {sigma}}{sub {ital ab}} is dramatically affected by the presence of small {ital T}{sub {ital C}} inhomogeneities, associated with small oxygen content inhomogeneities uniformly distributed in the crystals. These inhomogeneity effects are taken into account, consistently with our {Delta}{sigma}{sub {ital ab}} and {Delta}{chi}{sub {ital ab}} results, by using an effective medium approach proposed by Maza and Vidal. In this way, the amplitude and the {var_epsilon} behavior of the three observables studied here are explained in terms of the direct OPF effects, at a quantitative level, confirming then the absence of appreciable indirect contributions [as, for instance, the Maki-Thompson and the density-of-states (DOS) terms]. (Abstract Truncated)
- OSTI ID:
- 383190
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 10; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
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