Magnetic-field-induced supercurrent enhancement in hybrid superconductor/magnetic metal structures

TL;DR

This paper investigates how a parallel magnetic field can enhance the supercurrent in hybrid superconductor/magnetic metal tunnel structures by weakening the magnetic pair-breaking effects, revealing a novel interplay between superconductivity and magnetism.

Contribution

It predicts conditions under which magnetic fields enhance supercurrent in superconductor/magnetic metal tunnel structures, supported by experimental discussion.

Findings

Magnetic field can increase the tunnel critical current.

Conditions exist where magnetic effects weaken pair-breaking.

Interplay between superconducting and magnetic orders is experimentally discussed.

Abstract

The dc transport properties of the (S/M)I(M/S) tunnel structure - proximity coupled superconductor (S) and magnetic (M) layers separated by an insulator (I) - in a parallel magnetic field have been investigated. We choose for the M metal the one in which the effective magnetic interaction, whether it arises from direct exchange interaction or due to configuration mixing, aligns spins of the conducting electrons antiparallel to the localized spins of magnetic ions. For tunnel structures under consideration, we predict that there are the conditions when the destructive action of the internal and applied magnetic fields on Cooper pairs is weakened and the increase of the applied magnetic field causes the field-induced enhancement of the tunnel critical current. The experimental realization of the novel interesting effect of the interplay between superconducting and magnetic orders is also discussed.