Charged skyrmions on the surface of a topological insulator

TL;DR

This paper explores how magnetic skyrmions on an insulator surface coupled with a topological insulator can host bound states, become charged, and be manipulated via electric and magnetic fields, offering new control methods for skyrmion dynamics.

Contribution

It introduces a novel mechanism where skyrmions on a TI surface can host tunable bound states, enabling electric control of skyrmion charge and mobility.

Findings

Skyrmions can host a few bound states tunable by magnetic field.

Bound states are robust under external magnetic fields.

Charged skyrmions can be manipulated by electric fields.

Abstract

We consider the interplay between magnetic skyrmions in an insulating thin film and the Dirac surface states of a 3D topological insulator (TI), coupled by proximity effect. The magnetic texture of skyrmions can lead to confinement of Dirac states at the skyrmion radius, where out of plane magnetization vanishes. This confinement can result in charging of the skyrmion texture. The presence of bound states is robust in an external magnetic field, which is needed to stabilize skyrmions. It is expected that for relevant experimental parameters skyrmions will have a few bound states that can be tuned using an external magnetic field. We argue that these charged skyrmions can be manipulated directly by an electric field, with skyrmion mobility proportional to the number of bound states at the skyrmion radius. Coupling skyrmionic thin films to a TI surface can provide a more direct and efficient way of controlling skyrmion motion in insulating materials. This provides a new dimension in the study of skyrmion manipulation.