We demonstrate that the variation of the Andreev reflection with applied magnetic field provides a direct means of comparing the properties of MgB2 with the theory for a dirty two-band superconductor, and we find good agreement between the two. The ratio of electron diffusivities in the s and p bands can be inferred from this experiment. We find that the field dependence of the density of states at the Fermi level in the p band is independent of the field direction, and that the anisotropic upper critical field is determined by the anisotropic diffusivity in the s band.
@article{arxiv.cond-mat/0502153,
title = {Electron diffusivities in MgB2 from point contact spectroscopy},
author = {Y. Bugoslavsky and Y. Miyoshi and G. K. Perkins and A. D. Caplin and L. F. Cohen and A. V. Pogrebnyakov and X. X. Xi},
journal= {arXiv preprint arXiv:cond-mat/0502153},
year = {2009}
}