High magnetic field superconductivity in a two-band superconductor

TL;DR

This paper demonstrates that in a two-band superconductor, interband pairing can induce high-field reentrant superconductivity, surpassing traditional limits set by pairbreaking effects under magnetic fields.

Contribution

It introduces a mechanism where interband pairing leads to high-field reentrant superconductivity, violating the Pauli limit in two-band superconductors.

Findings

Interband pairing induces high-field reentrant superconductivity.

Superconductivity exceeds the Pauli-Chandrasekhar-Clogston limit.

Magnetic field effects are significantly altered by multiband interactions.

Abstract

When applying an external magnetic field to a superconductor, orbital and Pauli paramagnetic pairbreaking effects govern the limit of the upper critical magnetic field that can be supported before superconductivity breaks down. Experimental studies have shown that many multiband superconductors exhibit values of the upper critical magnetic field that violate the theoretically predicted limit, giving rise to many studies treating the underlying mechanisms that allow this. In this work we consider spin-splitting induced by an external magnetic field in a superconductor with two relevant bands close to the Fermi level, and show that the presence of interband superconducting pairing produces high-field reentrant superconductivity violating the Pauli-Chandrasekhar-Clogston limit for the value of the upper critical magnetic field.