Electromagnetic Proximity Effect: Superconducting Magnonics and Beyond

TL;DR

This paper reviews new phenomena arising from the non-contact dipolar interaction between magnons and superconductors in heterostructures, highlighting hybrid quasiparticles and control mechanisms for magnetization and energy transport.

Contribution

It introduces the concept of electromagnetic proximity effects in SC|FM heterostructures, revealing novel hybrid modes and control strategies for magnetism and superconductivity interactions.

Findings

Discovery of magnon-Meissner collective modes

Identification of magnon-cooparon and magnon-photon polaritons

Demonstration of gate-controlled magnetodipolar interactions

Abstract

The exchange interaction at interfaces between superconductors (SCs) and ferromagnets (FMs) has been a central topic in condensed matter physics for many decades, starting with the prediction of exotic phases such as the Fulde-Ferrell-Larkin-Ovchinnikov states and leading to the discovery of triplet superconductivity. This review focuses on new phenomena in SC$|$FM heterostructures caused by the \textit{non-contact dipolar interaction} between magnons, i.e., the quanta of spin wave excitations in the ferromagnet, and the superconducting order. A universal non-relativistic spin-orbit coupling locks the polarization and momentum of their evanescent stray magnetic fields and leads to chiral screening by proximate superconductors. The interaction-induced hybrid quasiparticles are magnon-Meissner collective modes, magnon-cooparon, Josephson plasmonic modes, and nodal magnon-photon polaritons. Superconducting and normal metallic gates modulate and control the magnetodipolar interaction and thereby magnetization and energy transport at interfaces and in thin films.