Twisted skyrmion at domain boundaries and the method of image

TL;DR

This paper predicts a new twisted skyrmion structure at antiferromagnetic domain boundaries, enabling controlled polarity switching via electric currents, and introduces the method of image for analyzing skyrmion-boundary interactions.

Contribution

It introduces a novel twisted skyrmion at domain boundaries and applies the method of image to analytically describe skyrmion-boundary interactions.

Findings

Twisted skyrmion can be switched between polarities by electric currents.

Analytical formula for skyrmion-boundary repulsive potential derived.

Micromagnetic simulations agree with theoretical predictions.

Abstract

We predict a novel twisted skyrmion structure at the boundary of two antiferromagnetically coupled magnetic domains with antiparallel magnetization directions. Through this intermediate state, skyrmions with opposite polarities can be freely switched between each other by spin-polarized electric currents. Based on these findings, we propose the concept of double-track skyrmion racetrack memory and logic gates where the binary data are represented by skyrmions with different polarities. The dynamics of skyrmion polarity reversal is theoretically studied. Using the method of image, we derive the analytical formula of the repulsive potential when a normal skyrmion approaches the domain boundary. A harmonic attractive potential well is obtained for the twisted skyrmion across the boundary. Micromagnetic simulations compare well with theoretical predictions. The method of image skyrmion proposed in this work can be used to deal with a large class of skyrmion-boundary interaction problems.