Dynamics of a magnetic skyrmionium in an anisotropy gradient

Abstract

A magnetic skyrmionium is a novel magnetization configuration with a zero skyrmion number, which can be viewed as a combination of two skyrmions with opposite skyrmion numbers. Here, we analytically and numerically study the dynamics of a skyrmionium under an anisotropy gradient. We find that the skyrmionium moves straight and can be efficiently driven by an anisotropy gradient with higher speed. Furthermore, skyrmionium deformation in a larger anisotropy gradient can be effectively suppressed by narrowing the width of the film. Our work shows an alternative driving method that may be promising for applications of skyrmionium-based racetrack memory. (C) 2019 The Japan Society of Applied Physics.