Chirality selective spin interactions mediated by the superconducting current

TL;DR

This paper demonstrates that superconducting currents can mediate chiral spin interactions, breaking inversion symmetry and enabling control over magnetic textures like skyrmions for spintronics.

Contribution

It introduces a novel mechanism where superconducting correlations induce chiral spin interactions, affecting magnetic textures and enabling external control via Josephson phase differences.

Findings

Energy differences between magnetic textures depend on chirality.

Josephson energies vary with magnetic helix and skyrmion topologies.

External phase difference controls magnetic texture energetics.

Abstract

We show that superconducting correlations in the presence of non-zero condensate velocity can mediate the peculiar interaction between localized spins that breaks the global inversion symmetry of magnetic moments. The proposed interaction mechanism is capable of removing fundamental degeneracies between topologically distinct magnetic textures. For the generic system of three magnetic impurities in the current-carrying superconductor we find the energy term proportional to spin chirality. In realistic superconductor/ferromagnetic/superconductor setups we reveal significant energy differences between various magnetic textures with opposite chiralities. We calculate Josephson energies of junctions through left and right-handed magnetic helices as well as through the magnetic skyrmions with opposite topological charges. Relative energy shifts between otherwise degenerate magnetic textures in these setups are regulated by the externally controlled Josephson phase difference. The suggested low-dissipative manipulation with the skyrmion position in a racetrack geometry can be used for the advanced spintronics applications.