Chirality-controlled spontaneous currents in spin-orbit coupled superconducting rings

TL;DR

This paper demonstrates that superconducting loops with ferromagnetic insulators exhibit spontaneous, chirality-dependent currents and magnetization-dependent critical temperatures, revealing new possibilities for superconducting spintronic devices.

Contribution

It introduces the concept of chirality-controlled spontaneous currents in spin-orbit coupled superconducting rings with ferromagnetic insulators.

Findings

Spontaneous currents with magnetization-dependent chirality form in the superconducting loop.

The critical temperature varies with the magnetization orientation.

Superconducting transition can influence the magnetization direction.

Abstract

At a superconductor interface with a ferromagnetic insulator (FI), the FI acts to induce a local exchange field within the S layer, which in the presence of spin-orbit interaction promotes a phase modulated superconducting state. Here we demonstrate that within a thin superconducting loop that is partially proximitized by a FI, spontaneous currents form with a magnetization-orientation-dependent chirality with sizable shifts in Little-Parks oscillations. Furthermore, the critical temperature of the loop is also magnetization-orientation-dependent and conversely, the superconducting transition itself may influence the magnetization direction. More generally, the superconducting region above the FI may serve as a phase battery and so offer a new device concept for superconducting spintronics.