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Excess current in point contacts on two-band superconductor MgB$_2$ in magnetic field

Yu. G. Naidyuk·O. E. Kvitnitskaya·I. K. Yanson·S. Lee·S. Tajima
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Abstract

Series of $I(V)$ characteristic and bias-dependent differential resistance $dV/dI(V)$ for point-contacts on the single crystals of two-band superconductor MgB$_2$ were measured in magnetic field up to 9 T. We have obtained magnetic field dependences of the excess current on the $I(V)$ curves and analyzed them using Koshelev and Golubov (Phys. Rev. Lett. {\bf 90}, 177002 (2003)) theoretical results for the mixed state of a dirty two-band superconductor. Introducing a simple model for the excess current in the point contact in the mixed state our data can be qualitatively described utilizing theoretical magnetic filed behavior of the $σ$ and $π$-band superconducting order parameters and the corresponding averaged electronic density of states in MgB$_2$.

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Yu. G. Naidyuk, O. E. Kvitnitskaya, I. K. Yanson, S. Lee, S. Tajima. 2004-10-25. Excess current in point contacts on two-band superconductor MgB$_2$ in magnetic field. https://doi.org/10.1016/j.ssc.2004.11.037

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