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Thermally-activated current transport in MgB_2 films

S. Patnaik·A. Gurevich·S. D. Bu·J. Choi·C. B. Eom·D. C. Larbalestier
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Abstract

Thermally-activated flux flow (TAFF) resistivity above the irreversibility field is reported for two different c-axis textured MgB_2 superconducting films. Transport measurements at different perpendicular magnetic fields 0 < B < 9 T and temperatures from 5 to 40K reveal TAFF Ohmic resistivity described by the Arrhenius law with the quadratic field dependence of the activation energy. Our transport measurements on bulk MgB_2 ceramic samples also show the TAFF behavior, but do not show the quadratic field dependence of U(T,B). We explain our results in terms of thermally-activated drift of pre-existing quenched dislocations in the vortex lattice. Our results indicate that thermal fluctuations can be essential in determining the irreversibility field in MgB2 though to a much lesser extent than in high-temperature superconductors.

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S. Patnaik, A. Gurevich, S. D. Bu, J. Choi, C. B. Eom, D. C. Larbalestier. 2004-06-12. Thermally-activated current transport in MgB_2 films. https://doi.org/10.1103/physrevb.70.064503

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