Overcoming the speed limit in skyrmion racetrack devices by suppressing the skyrmion Hall effect

TL;DR

This paper demonstrates that suppressing the skyrmion Hall effect in racetrack devices significantly increases the maximum skyrmion velocity, enabling faster data propagation by allowing larger driving currents and straight-line skyrmion motion.

Contribution

It introduces a method to suppress the skyrmion Hall effect using spin current polarization, enhancing skyrmion velocity in racetrack devices.

Findings

Maximum skyrmion velocity increases by a factor of 10 when the Hall effect is suppressed.

Partial polarization of spin current reduces the skyrmion Hall angle.

Analytical and simulation results confirm conditions for complete suppression.

Abstract

Magnetic skyrmions are envisioned as carriers of information in racetrack storage devices. Unfavorably, the skyrmion Hall effect hinders the fast propagation of skyrmions along an applied electric current and limits the device's maximum operation speed. In this Rapid Communication, we show that the maximum skyrmion velocity increases by a factor of 10 when the skyrmion Hall effect is suppressed, since the straight-line motion of the skyrmion allows for the application of larger driving currents. We consider a ferromagnet on a heavy metal layer, which converts the applied charge current into a spin current by the spin Hall effect. The spin current drives the skyrmions in the ferromagnet via spin-orbit torque. We show by analytical considerations and simulations that the deflection angle decreases, when the spin current is polarized partially along the applied current direction and derive the condition for complete suppression of the skyrmion Hall effect.