Generalized Gor’kov relation for two-band superconductor MgB2

A generalized Gor’kov relation between the upper critical magnetic field Hc2, the residual resistivity, and the parameters of the two-band electronic structure from the pure limit to the dirty limit was derived for two-gap superconductor MgB2. The ratio of the relaxation times τπ/τσ of π-and σ-band electrons for MgB2 samples with various defect levels was determined from experimental data.