Current-induced motion of twisted skyrmions

TL;DR

This paper explores the unique magnetic structure and current-driven dynamics of twisted skyrmions, revealing how their motion depends on helicity and damping, with implications for skyrmion-based memory devices.

Contribution

It provides the first detailed micromagnetic simulation analysis of twisted skyrmion dynamics driven by STT and SHE, highlighting the role of helicity and damping.

Findings

Skyrmion Hall angle depends on helicity for SHE-induced motion.

Trajectory control achieved via Gilbert damping gradient.

Twisted skyrmion motion characterized by relation to dissipative tensor.

Abstract

Twisted skyrmions, whose helicity angles are different from that of Bloch skyrmions and N\'eel skyrmions, have already been demonstrated in experiments recently. In this work, we first contrast the magnetic structure and origin of the twisted skyrmion with other three types of skyrmion including Bloch skyrmion, N\'eel skyrmion and antiskyrmion. Following, we investigate the dynamics of twisted skyrmions driven by the spin transfer toque (STT) and the spin Hall effect (SHE) by using micromagnetic simulations. It is found that the spin Hall angle of the twisted skyrmion is related to the dissipative force tensor and the Gilbert damping both for the motions induced by the STT and the SHE, especially for the SHE induced motion, the skyrmion Hall angle depends substantially on the skyrmion helicity. At last, we demonstrate that the trajectory of the twisted skyrmion can be controlled in a two dimensional plane with a Gilbert damping gradient. Our results provide the understanding of current-induced motion of twisted skyrmions, which may contribute to the applications of skyrmion-based racetrack memories.