Nonlinear Superconducting Magnetoelectric Effect

TL;DR

This paper predicts a nonlinear magnetoelectric effect in superconductor heterostructures, where supercurrent induces a second-order spin polarization, offering a new, non-dissipative way to control magnetization in superconducting spintronics.

Contribution

It introduces the concept of a nonlinear superconducting magnetoelectric (NSM) effect that persists in centrosymmetric systems and is the dominant magnetic response in various magnetic materials.

Findings

NSM manifests as a second-order response to supercurrent.

NSM survives centrosymmetry and dominates in certain magnetic materials.

Potential for electric, non-dissipative control of magnetization in heterostructures.

Abstract

Supercurrent flow can induce a nonvanishing spin magnetization in noncentrosymmetric superconductors with spin-orbit interaction. Often known as the non-dissipative magnetoelectric effect, these are most commonly found at linear order in supercurrent flow. Here, we propose that a {\it nonlinear} superconducting magnetoelectric (NSM) effect can naturally manifest in magnet/superconductor heterostructures. In such platforms, NSM manifests as the spin polarization generated as a second-order response to a driving supercurrent. Strikingly, we find NSM survives centrosymmetry and is the leading order magnetic response in a variety of magnetic materials that include both collinear magnets [e.g., $d$-wave planar altermagnet thin film/superconductor (ALM/SC)] as well as noncollinear magnets (e.g., Kagome/SC systems). This renders NSM a powerful electric and non-dissipative means of controlling magnetization in magnet/superconductor heterostructures, a promising platform for superconducting spintronics.