Triplet contribution to the Josephson current in the nonequilibrium superconductor/ferromagnet/superconductor junction

TL;DR

This paper theoretically investigates how nonequilibrium spin-dependent occupations in a superconductor/ferromagnet/superconductor junction induce a triplet supercurrent component, affecting the overall Josephson current and junction states.

Contribution

It introduces the concept of triplet contribution to the Josephson current under nonequilibrium conditions, revealing its impact on current magnitude and 0-$oldsymbol{ extpi}$ state switching.

Findings

Triplet supercurrent component appears under nonequilibrium conditions.

The triplet current can enhance or suppress the total Josephson current.

Voltage control can switch the junction between 0- and $ extpi$-states.

Abstract

The Josephson current through a long s-wave superconductor/weak ferromagnet/s-wave superconductor weak link is studied theoretically in the regime of nonequilibrium spin-dependent occupation of electron states in the ferromagnetic intelayer. While under the considered nonequilibrium condition the standard supercurrent, carried by the singlet part of current-carrying density of states, is not modified, the additional supercurrent flowing via the triplet part of the current-carrying density of states appears. Depending on voltage, controlling the particular form of spin-dependent nonequilibrium in the interlayer, this additional current can enhance or reduce the usual current of the singlet component and also switch the junction between 0- and $\pi$-states.