Current-driven dynamics and ratchet effect of skyrmion bubbles in a ferrimagnetic insulator

TL;DR

This paper demonstrates room temperature control and manipulation of skyrmion bubbles in a ferrimagnetic insulator, revealing their dynamics, Hall effect, and a magnetic ratchet mechanism for potential memory and computing applications.

Contribution

It introduces a method to stabilize and control skyrmion bubbles at room temperature in TmIG/Pt, including a novel ratchet effect for directional skyrmion motion.

Findings

Skyrmion bubbles exhibit a strong Hall effect with negative deflection.

Velocity and depinning thresholds are tunable via exchange coupling.

A magnetic ratchet effect enables directional control of skyrmion flow.

Abstract

Magnetic skyrmions are compact chiral spin textures that exhibit a rich variety of topological phenomena and hold potential for developing high-density memory devices and novel computing schemes driven by spin currents. Here, we demonstrate room temperature interfacial stabilization and current-driven control of skyrmion bubbles in the ferrimagnetic insulator Tm3Fe5O12 (TmIG) coupled to Pt. We track the current-induced motion of individual skyrmion bubbles. The ferrimagnetic order of the crystal together with the interplay of spin-orbit torques and pinning determine the skyrmion dynamics in TmIG and result in a strong skyrmion Hall effect characterized by a negative deflection angle and hopping motion. Further, we show that the velocity and depinning threshold of the skyrmion bubbles can be modified by exchange coupling TmIG to an in-plane magnetized Y3Fe5O12 layer, which distorts the spin texture of the skyrmions and leads to a directional-dependent rectification of their dynamics. This effect, which is equivalent to a magnetic ratchet, is exploited to control the skyrmion flow in a racetrack-like device.