Field dependence of the vortex-core size in dirty two-band superconductors

We study the structure of Abrikosov vortices in two-band superconductors for different external magnetic fields and different parameters of the bands, including the interband scattering rate. The vortex-core size determined by the coherence lengths is found to have qualitatively different behavior from that determined by the quasiparticle density of states spatial variation. These different vortex-core length scales coincide near the upper critical field, while the discrepancy between them becomes quite significant at lower fields. Within the diffusive approximation we demonstrate several generic regimes in the field dependence of the vortex-core sizes determined by the disparity of diffusion constants in the two bands, interband pairing, and interband scattering rate.