Intertype superconductivity evoked by the interplay of disorder and multiple bands

TL;DR

This paper reveals that disorder in multiband superconductors can significantly expand the intertype domain, leading to a transition from type I to deep type-II superconductivity, which differs from single-band behavior.

Contribution

It demonstrates that multiband structure and differing band diffusivities cause a substantial expansion of the intertype domain due to disorder effects.

Findings

Disorder can induce a transition from type I to type II superconductivity in multiband systems.

The intertype domain expands significantly when band diffusivities differ.

Deep type-II behavior can emerge in disordered multiband superconductors.

Abstract

Nonmagnetic impurity scattering is known to shift up the Ginzburg-Landau parameter $\kappa$ of a superconductor. In this case, when the system is initially in type I, it can change its magnetic response, crossing the intertype domain with $\kappa \sim 1$ between the two standard superconductivity types and arriving at type II. In the present work we demonstrate that the impact of disorder can be much more profound in the presence of the multiband structure of the charge carrier states. In particular, when the band diffusivities differ from each other, the intertype domain tends to expand significantly, including points with $\kappa \gg 1$ that belong to deep type-II in conventional single-band superconductors. Our finding sheds light on the nontrivial disorder effect and significantly complements earlier results on the enlargement of the intertype domain in clean multiband superconductors.