Recovering of superconductivity in exchange fields exceeding Pauli limiting field under spin-dependent quasiparticle distribution

TL;DR

This paper theoretically demonstrates that spin-dependent quasiparticle distributions can counteract Zeeman pair-breaking effects, enabling superconductivity to be restored even under exchange fields surpassing the Pauli limit.

Contribution

It introduces a method to recover superconductivity in high exchange fields by using spin accumulation potentials, surpassing previous limitations.

Findings

Superconductivity can be restored with appropriate spin accumulation.

Exchange fields exceeding the Pauli limit do not suppress superconductivity with this method.

Proposed experimental setup involves voltage-biased junctions with half metals.

Abstract

We study theoretically the simultaneous influence of spin accumulation potential $eV_\uparrow-eV_\downarrow$ and the Zeeman exchange field on singlet superconductivity. It is shown that the pair-breaking effect of the Zeeman field can be fully compensated by creation of the appropriate spin accumulation potential in the superconductor. Moreover, superconductivity can be recovered for exchange fields well exceeding the Pauli limiting field. It is proposed that the effect can be experimentally realized on the basis of voltage biased junction consisting of a thin superconducting film sandwiched between two half metals.