Coupling of skyrmions mediated by RKKY interaction

TL;DR

This paper investigates how RKKY interaction mediates coupling between skyrmions in a bi-layer system, revealing attractive or repulsive forces depending on spacer thickness and their effects on skyrmion dynamics.

Contribution

It provides analytical solutions for skyrmion positions under RKKY interaction and demonstrates potential for skyrmion manipulation in multilayer devices.

Findings

RKKY interaction can be attractive or repulsive based on spacer thickness.

Skyrmion widths decrease with increasing RKKY energy at larger distances.

Attractive RKKY interaction induces skyrmion precessory motion.

Abstract

A discussion on the interaction between skyrmions in a bi-layer system connected by a non-magnetic metal is presented. From considering a free charge carrier model, we have shown that the Ruderman-Kittel-Kasuya-Yosida (RKKY ) inter- action can induce attractive or repulsive interaction between the skyrmions depending on the spacer thickness. We have also shown that due to an increasing in RKKY energy when the skyrmions are far from each other, their widths are diminished. Finally, we have obtained analytical solutions to the skyrmion position when the in-plane distance between the skyrmions is small and it is shown that an attractive RKKY interaction yields a skyrmion precessory motion. This RKKY-induced coupling could be used as a skyrmion drag mechanism to displace skyrmions in multilayers.