Counterpart of the Chandrasekhar-Kendall state in noncentrosymmetric superconductors

TL;DR

This paper introduces 'toroflux', a new stable, localized magnetic field configuration in noncentrosymmetric superconductors, analogous to astrophysical spheromaks, characterized by non-zero helicity and toroidal magnetic moments.

Contribution

It presents the theoretical discovery of toroflux states in noncentrosymmetric superconductors, extending the concept of Chandrasekhar-Kendall states to superconducting materials.

Findings

Toroflux solutions are stable, localized magnetic configurations in noncentrosymmetric superconductors.

These solutions exhibit non-zero magnetic helicity and toroidal dipole moments.

Magnetic dipoles or ferromagnetic inclusions can source finite-energy toroflux states.

Abstract

We demonstrate that superconductors with broken inversion symmetry support a family of stable, spatially localized configurations of the self-knotted magnetic field. These solutions, that we term ``toroflux,'' are the superconducting counterparts of the Chandrasekhar-Kendall states (spheromaks) that appear in highly conducting, force-free astrophysical and nuclear-fusion plasmas. The superconducting torofluxes are solutions of superconducting models, in the presence of a parity-breaking Lifshitz invariant associated with the $O$ point-group symmetry. These solutions are characterized by a non-vanishing helicity of the magnetic field, and also by a toroidal dipole moment of the magnetic field. We demonstrate that a magnetic dipole or a ferromagnetic inclusion in the bulk of a noncentrosymmetric superconductor sources finite-energy toroflux solutions.