Dzyaloshinskii-Moriya-type spin-spin interaction from mixed-parity superconductivity

TL;DR

This paper demonstrates that a Dzyaloshinskii-Moriya-type interaction can emerge purely from superconducting correlations in mixed-parity superconductors, enabling control of spin textures without relying on spin-orbit coupling.

Contribution

It reveals a novel mechanism for DMI-like interactions arising solely from superconducting pairing, expanding possibilities for spin texture engineering.

Findings

DMTI arises in mixed-parity superconductors from pairing.

DMTI can be toggled in Josephson junctions via phase bias.

Superconducting correlations can induce spin interactions without spin-orbit coupling.

Abstract

Interacting impurity spins adsorbed on surfaces have been suggested as basic components for applications in quantum computation and spintronics. Such spins usually prefer a parallel or antiparallel configuration, but weakly non-collinear alignments are possible due to the Dzyaloshinskii-Moriya interaction (DMI) that arises in the presence of relativistic spin-orbit coupling. Here, we show that an effective Dzyaloshinskii-Moriya-type interaction (DMTI) can emerge purely from superconducting correlations without any spin-orbit interaction. We give an analytical proof and provide a numerical study which shows that DMTI arises in mixed-parity superconductors solely from the superconducting pairing. Moreover, we show that the same effect can be realized in Josephson junctions between s-wave and p-wave superconductors, where a phase bias toggles the DMTI entirely on and off. These results enable a way to engineer spin textures using superconducting order.