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Anisotropy of superconducting MgB2 as seen in electron spin resonance and magnetization data

F. Simon·A. Janossy·T. Feher·F. Muranyi·S. Garaj·L. Forro·C. Petrovic·S. L. Bud'ko·G. Lapertot·V. G. Kogan·P. C. Canfield
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Abstract

We have observed the conduction electron spin resonance (CESR) in fine powders of MgB2 both in the superconducting and normal states. The Pauli susceptibility is chi_s=2.0*10^{-5} emu/mole in the temperature range of 450 to 600 K. The spin relaxation rate has an anomalous temperature dependence. The CESR measured below T_c at several frequencies suggests that MgB_2 is a strongly anisotropic superconductor with the upper critical field, H_c2, ranging between 2 and 16 T. The high-field reversible magnetization data of a randomly oriented powder sample are well described assuming that MgB_2 is an anisotropic superconductor with H_c2^{ab} / H_{c2}^{c} \approx 6--9.

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F. Simon, A. Janossy, T. Feher, F. Muranyi, S. Garaj, L. Forro, C. Petrovic, S. L. Bud'ko, G. Lapertot, V. G. Kogan, P. C. Canfield. 2001-04-28. Anisotropy of superconducting MgB2 as seen in electron spin resonance and magnetization data. https://doi.org/10.1103/physrevlett.87.047002

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