Nonequilibrium Transport in Superconductor/Ferromagnet/Superconductor Diffusive Junctions: Interplay between Proximity Effect and Ferromagnetism

TL;DR

This paper develops a theory for the current-voltage characteristics of diffusive superconductor/ferromagnet/superconductor junctions, revealing how ferromagnetic exchange fields influence conductance peaks and current behavior.

Contribution

It introduces a theoretical framework that captures the interplay between proximity effect and ferromagnetism in SFS junctions, highlighting the impact of exchange fields on transport properties.

Findings

Exchange field causes an additional conductance peak at eV ~ Δ+h.

Excess current shows non-monotonous dependence on the exchange field.

Temperature behavior of current is strongly affected by the exchange field's temperature dependence.

Abstract

The theory of the I-V characteristics in diffusive superconductor/weak ferromagnet/superconductor (SFS) junction is developed. We show that the exchange field $h$ of the ferromagnet manifests itself as an additional conductance peak at $eV \sim \Delta+h$ in the phase-coherent regime, when the Thouless energy is of the order of superconducting order parameter. The excess current exhibits non-monotonous dependence on the exchange field and non-trivial temperature behavior, which is strongly influenced by the temperature dependence of the exchange field.