Mixed state of a dirty two-band superconductor: application to MgB_2

TL;DR

This paper studies the vortex state in a two-band superconductor with impurity scattering, revealing two distinct length scales and interpreting STM experiments on MgB_2.

Contribution

It introduces a numerical solution of coupled Usadel equations for two-band superconductors with impurities, highlighting two length scales and explaining experimental vortex imaging.

Findings

Identification of two distinct length scales in vortex structures.

Qualitative interpretation of STM vortex imaging in MgB_2.

Numerical analysis of pair potentials and local densities of states.

Abstract

We investigate the vortex state in a two-band superconductor with strong intraband and weak interband electronic scattering rates. Coupled Usadel equations are solved numerically and the distributions of the pair potentials and local densities of states are calculated for two bands at different values of magnetic fields. The existence of two distinct length scales corresponding to different bands is demonstrated. The results provide qualitative interpretation of recent STM experiments on vortex structure imaging in MgB_2.