Phys. Rev. B 72, 224506 (2005) [5 pages]Electron diffusivities in MgB2 from point contact spectroscopyReceived 23 March 2005; revised 17 August 2005; published 9 December 2005 We quantify the underlying physical mechanism behind the variation of the Andreev reflection with applied magnetic field in MgB2 epitaxial film and find good agreement with the theory for a dirty two-band superconductor. The important microscopic property, the ratio of electron diffusivities in the σ and π bands can be measured directly by means of Andreev reflection. We analyze results obtained for different directions of the applied field and determine the anisotropy of the diffusivities demonstrating that the anisotropic upper critical field is determined solely by the anisotropic diffusivity in the σ band. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.72.224506
DOI:
10.1103/PhysRevB.72.224506
PACS:
74.70.Ad, 74.25.Ha, 74.50.+r
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