Supercurrent-induced long-range triplet correlations and controllable Josephson effect in superconductor/ferromagnet hybrids with extrinsic SOC

TL;DR

This paper predicts that supercurrent flowing in superconductor/ferromagnet hybrids with extrinsic spin-orbit coupling can generate and control long-range triplet correlations, enabling a controllable 0-π Josephson junction switch.

Contribution

It introduces mechanisms for supercurrent-induced long-range triplet correlations in S/F hybrids with extrinsic SOC, and demonstrates controllable 0-π phase switching in Josephson junctions.

Findings

Long-range triplet correlations can be generated via supercurrent and SOC.

The 0-π phase switch can be controlled by reversing the supercurrent.

The mechanisms involve spin Hall effect and spin current swapping.

Abstract

We predict that long-range triplet correlations (LRTC) in superconductor/ferromagnet (S/F) hybrids with extrinsic impurity spin-orbit coupling (SOC) can be generated and manipulated by supercurrent flowing in the superconducting leads along the S/F interfaces. The LRTC appear via two basic mechanisms. The essence of the first one is the generation of triplets by the superconducting spin Hall effect. These pairs are long-range in the ferromagnet under the appropriate mutual orientation of the condensate momentum and the ferromagnet magnetization. The second mechanism is based on the singlet-triplet conversion at the S/F interface followed by the rotation of the spin of the obtained short-range opposite-spin pairs via the spin current swapping mechanism. The structure of the supercurrent-induced LRTC is studied both for S/F bilayers and S/F/S Josephson junctions. We demonstrate that in S/F/S junctions, where the Josephson coupling is realized via the supercurrent-induced LRTC, the ground state phase can be switched between $0$ and $\pi$ in a controllable manner. The switching is performed by reversing the supercurrent in one of superconducting leads, thus realizing a new physical principle of the $0-\pi$ shifter.