Two-band Effects in the Angular Dependence of Hc2 of MgB2 Single Crystals

Abstract

The angular dependence of the upper critical field Hc2 of MgB2 single crystals is studied at various temperatures by means of specific heat and transport measurements in magnetic fields up to 17 T. Clear deviations from Ginzburg-Landau behavior are observed at all temperatures and are explained by two-band effects. The angular- and temperature dependence of the deviations are in qualitative agreement with theoretical predictions based on band-structure calculations. Quantitative agreement is obtained with an interband coupling slightly stronger than the calculated, enabling band-structure anisotropies and interband coupling strength to be experimentally estimated. This provides a new pathway to the study of disorder and doping effects in MgB2.

arXiv comment4 pages, 4 figures

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• The influence of weak texture on the critical currents in polycrystalline MgB${}_2$
• Anisotropy and Penetration Depth of MgB${}_2$ from ${}^{11}$B NMR
• Magnetic field induced orientation of superconducting MgB${}_2$ crystallites determined by X-ray diffraction