Theoretical Study of Current-Induced Dynamics of an Antiferromagnetic Skyrmionium

Abstract

In this thesis, we present a theoretical study on the current-induced nucleation and propagation of antiferromagnetic skyrmionium. A skyrmionium, also known as 2π-skyrmion, is a vortex-like magnetic structure characterized by zero topological charge. We show by means of micro-magnetic simulation that an antiferromagnetic skyrmionium can be nucleated via a local injection of spin current with toroidal distribution. Our systematic study of the current-induced dynamics shows that a spatially uniform spin current induces propagation of antiferromagnetic skyrmionium with measurable distortion at high current densities. We derive expression for the velocity of the antiferromagnetic skyrmionium based on the collective-coordinate model and obtain good agreement with our numerical results.