Comment on “Superconducting anisotropy and evidence for intrinsic pinning in single crystalline MgB2”

Abstract

In a recent paper [Phys. Rev. B 66, 012501 (2002)], torque data measured on a MgB2 single crystal in fields from 10to60kOe at 10K were presented. The authors obtained the anisotropy γ by fitting a theoretical expression to the data and concluded that the anisotropy is field-independent, γ≈4.3. In this Comment, we show that the above conclusion does not hold, because it was obtained based on the analysis of torque data measured in fields close to or above the upper critical field Hc2, where the theoretical expression used is not applicable. Furthermore, we argue that the experimental torque data with H⪡Hc2 indicate an anisotropy strongly increasing with increasing field.

Source-reported materials — not catalogue approval

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