Manipulation of hybrid skyrmion dynamics by step DMI approach

Abstract

The dynamic behavior of non-collinear atomic spin arrangements in a topologically protected magnetic skyrmion plays a pivotal role in potential future spintronic technologies, including racetrack memory based ultra-high-density storage devices. However, the topological nature of the skyrmion comes with an unwanted skyrmion Hall effect (SkHE) that poses a significant challenge in the practical application. Here we present a detailed micromagnetic simulation study that delves into the controlled manipulation of skyrmion dynamics through a subtle engineering of Dzyaloshinskii-Moriya interaction (DMI) in a hybrid skyrmion racetrack. In particular, we introduce a gradient variation of bulk and interfacial DMI that results into a parabolic trajectory of Skyrmion Hall angle (SkHA), thereby allowing us to find a critical DMI ratio with almost zero SkHE. Most importantly, we present a novel approach involving engineering of a racetrack with strategically placed step DMI regions that gives us a meticulous control over the size and speed of the hybrid skyrmions. The present study gives a new direction for the simultaneous realization of stable skyrmions without SkHE and increased skyrmion speed with optimized DMI engineering.