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Temperature and field dependence of the anisotropy of MgB2

M. Angst·R. Puzniak·A. Wisniewski·J. Jun·S. M. Kazakov·J. Karpinski·J. Roos·H. Keller
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Abstract

The anisotropy gamma of the superconducting state of high quality single-crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature dependent, decreasing from gamma = 6 at 15 K to 2.8 at 35 K. Reversible torque data near Tc reveal a field dependent anisotropy, increasing nearly linearly from gamma = 2 in zero field to 3.7 in 10 kOe. The unusual temperature dependence is a true bulk property and can be explained by non-local effects of anisotropic pairing and/or the wave vector dependence of the effective mass tensor.

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M. Angst, R. Puzniak, A. Wisniewski, J. Jun, S. M. Kazakov, J. Karpinski, J. Roos, H. Keller. 2002-03-16. Temperature and field dependence of the anisotropy of MgB2. https://doi.org/10.1103/physrevlett.88.167004

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