Spin-spin interaction mediated by chiral phonons

TL;DR

This paper investigates how chiral phonons mediate spin-spin interactions between magnetic impurities on a 2D insulator, revealing a positive, temperature-dependent exchange that decays with distance.

Contribution

It provides analytical expressions for phonon-mediated exchange interactions, highlighting the role of phonon angular momentum and spin-chiral phonon coupling.

Findings

Exchange interaction is always positive due to phonons' bosonic nature.

Interaction decays as a power law with distance.

At high temperature, interaction strength is proportional to temperature.

Abstract

We study interaction between two magnetic impurities on top of a two dimensional insulator in the presence of chiral phonons by second-order perturbation theory. We show that this exchange interaction arises from angular momentum of phonons through spin-chiral phonon interaction of the form of spin-orbit coupling. Analytical expressions of the interaction for acoustic and optical phonons are obtained. The exchange interactions are always positive due to the bosonic nature of phonons. We find that the exchange interactions for acoustic and optical phonons show power-law decay with respect to the distance between the two magnetic impurities and are proportional to the temperature of the system at high temperature.