Electric-field driven stability control of skyrmions in an ultrathin transition-metal film

TL;DR

This paper demonstrates how external electric fields can control the stability and lifetime of magnetic skyrmions in ultrathin transition-metal films, enabling potential electric-field assisted writing and deleting for spintronic applications.

Contribution

It provides a detailed microscopic understanding of how electric fields influence skyrmion stability by considering all relevant magnetic interactions through first-principles calculations and atomistic simulations.

Findings

Electric fields significantly alter skyrmion energy barriers.

Skyrmion size and lifetime are highly sensitive to electric fields.

Electric-field control enables thermally activated skyrmion writing and deleting.

Abstract

To realize future spintronic applications with magnetic skyrmions -- topologically nontrivial swirling spin structures -- it is essential to achieve efficient writing and deleting capabilities of these quasi-particles. Electric-field assisted nucleation and annihilation is a promising route, however, the understanding of the underlying microscopic mechanisms is still limited. Here, we show how the stability of individual magnetic skyrmions in an ultrathin transition-metal film can be controlled via external electric fields. We demonstrate based on density functional theory that it is important to consider the changes of all interactions with electric field, i.e., the pair-wise exchange, the Dzyaloshinskii-Moriya interaction, the magnetocrystalline anisotropy energy, and the higher-order exchange interactions. The energy barriers for electric-field assisted skyrmion writing and deleting obtained via atomistic spin simulations vary by up to a factor of three more than the variations of the interactions calculated from first-principles. This surprising effect originates from the electric-field dependent size of metastable skyrmions at a fixed magnetic field. The large changes of lifetimes allow the possibility of electric-field assisted thermally activated writing and deleting of skyrmions.