Thermal fluctuation effects on the magnetization above and below the superconducting transition in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals in the weak magnetic field limit
- Laboratorio de Fisica de Materiales, Facultad de Fisica, Universidad de Santiago de Compostela, 15706 (Spain)
- Departamento de Cristalografia, Facultad de Ciencias Geologicas, Universidad Complutense de Madrid, Madrid, 28040 (Spain)
- Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Cientificas, Cantoblanco, Madrid, 28049 (Spain)
We present detailed experimental data of the magnetization, {ital M}{sub {ital ab}}({ital T},{ital H}), of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals on both sides of the superconducting transition, for magnetic fields, {ital H}, applied perpendicularly to the {ital ab} (CuO{sub 2}) planes and for amplitudes up to {mu}{sub 0}{ital H}=5 T, which not too close to the superconducting transition correspond to the weak magnetic field amplitude limit. These data are analyzed in terms of thermal fluctuations in this weak {ital H} limit: In the reversible mixed state below the transition, by taking into account the fluctuations of the vortex lines positions, as first proposed by Bulaevskii, Ledvij, and Kogan. Above the transition, by taking into account the Cooper pairs created by thermal fluctuations, through a generalization of multilayered superconductors of the Schmidt-like approach. These simultaneous, quantitative and consistent analyses of {ital M}{sub {ital ab}}({ital T},{ital H}) above and below the transition allow us to estimate the effective number of independent fluctuating superconducting CuO{sub 2} planes in the periodicity length {ital s}={ital c}/2, {ital c} being the unit-cell length, and to separate for the first time the in-plane correlation length amplitude, {xi}{sub {ital ab}}(0), and the parameter related to the vortex structure, {eta}. We found {xi}{sub {ital ab}}(0)=(0.8{plus_minus}0.1) nm and {eta}=0.15{plus_minus}0.05, this last value being well within the one calculated by Fetter by applying the London model to a triangular vortex lattice. For the in-plane magnetic penetration depth, we found a temperature behavior compatible with the clean BCS weak coupling limit, and an amplitude (at {ital T}=0 K) of {lambda}{sub {ital ab}}(0)=(180{plus_minus}20) nm. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 284709
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 22; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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