Superconducting fluctuations in the thermal conductivity of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} and DyBa{sub 2}Cu{sub 3}O{sub 7{minus}x} materials
- SUPRAS, Institute of Physics B5, University of Liege, B-4000 Liege (Belgium)
- SUPRAS, Institute of Chemistry B6, University of Liege, B-4000 Liege (Belgium)
The thermal conductivity {kappa} of Bi{sub 2}Sr{sub 1.8}Ca{sub 1.2}Cu{sub 2}O{sub 8} and DyBa{sub 2}Cu{sub 2}O{sub 7{minus}x} polycrystals is analyzed near the critical temperature (T{sub c}=79.5 and 83.8 K, respectively) in order to extract the superconducting fluctuation contribution {kappa}{sub fl}. The fluctuationless background is calculated in a formal way, taking into account both an electronic and a phonon contribution above and below the critical temperature. The fluctuation contribution to the electronic thermal conductivity is then extracted. A crossover from a critical to a Gaussian fluctuation regime ({vert_bar}T{sub G}{minus}T{sub c}{vert_bar}{approx}2.2K) is observed on the Bi{sub 2}Sr{sub 1.8}Ca{sub 1.2}Cu{sub 2}O{sub 8} sample both above and below T{sub c}, followed by a crossover from a three-dimensional (3D) to a 2D Gaussian behavior ({vert_bar}T{sub VL}{minus}T{sub c}{vert_bar}{approx}3.7K) as the sample temperature is further moved away from T{sub c}. On the other hand, a 3D behavior only is observed on the DyBa{sub 2}Cu{sub 2}O{sub 7{minus}x} material in the normal and superconducting states. In both systems, the critical exponents are found to be those theoretically predicted. Moreover, the crossover temperatures are consistent with those expected from the differently anisotropic structures of these compounds. From the crossover temperatures and the thermal conductivity fluctuation contribution amplitudes, quite realistic values for the Ginzburg-Landau parameter k{sub GL}, the interlayer coupling energy J{sub c}, and the electronic mean free path l{sub e} near T{sub c} are found in those materials. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 549305
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 2 Vol. 56; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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