Description
We have developed a theoretical framework to study
nonequilibrium processes in multiband superconductors
based on microscopic kinetic theory and applied it to calculate
flux-flow resistivity of such systems in the dirty limit with a
high concentration of nonmagnetic impurities. We have
considered both the regions of high and low magnetic fields.
To calculate the conductivity in the former case, we have
derived the solution characterizing moving vortex lattices,
which reveals the effect of splitting into sublattices of
fractional vortices.
It is shown that in contrast to single-band superconductors,
the resistive properties are not universal but depend on the
pairing constants and ratios of diffusivities in different bands.
This naturally explains quite diverse experimental data on the
flux-flow resistivity in different multiband superconducting
compounds.
By choosing the ratio of diffusivities in two bands, D2/D1 =
2.5, we have obtained a quantitative agreement with
experimental data for MgB2. In this case, the low-field
magnetoresistance strongly exceeds
the Bardeen-Stephen estimation.
