Tuning of a skyrmion cluster in magnetoelectric Cu$_2$OSeO$_3$ by electric field

TL;DR

This study demonstrates the electric field control of skyrmion clusters in the magnetoelectric compound Cu$_2$OSeO$_3$, showing linear skyrmion number increase and estimating the energy for skyrmion creation.

Contribution

It provides the first in situ evidence of electric field writing and erasing of skyrmion clusters in Cu$_2$OSeO$_3$, expanding understanding of electric manipulation of topological magnetic textures.

Findings

Skyrmion number increases linearly with electric field.

Energy to create a single skyrmion is estimated at 4.7 x 10^{-24} J.

Electric field can write and erase skyrmions in clusters.

Abstract

Chiral magnetic textures with non-trivial topology are known as skyrmions, and due to their unique properties they are promising in novel magnetic storage applications. While the electric manipulation of either isolated skyrmions or a whole skyrmion lattice have been intensively reported, the electric effects on skyrmion clusters remain scarce. In magnetoelectric compound Cu$_2$OSeO$_3$, a skyrmion cluster can be created near the helical-skyrmion phase boundary. Here, we report the in situ electric field writing/erasing of skyrmions in such a skyrmion cluster. Our real space/time image data obtained by Lorentz transmission electron microscopy and the quantitative analysis evidence the linear increase of the number of skyrmions in the cluster upon the application of a creating electric field. The energy needed to create a single skyrmion is estimated to be $\mathcal{E}=4.7 \times 10^{-24}$ J.