Room-Temperature Current-Induced Generation and Motion of sub-100 nm Skyrmions

TLDR

Magnetic skyrmions are nanoscale spin windings with topology‑related properties that promise technological applications, and recent room‑temperature observations of sub‑100 nm skyrmions in multilayers raise questions about how to nucleate individual compact skyrmions and control their motion. The study demonstrates a method to nucleate magnetic skyrmions in a micrometer‑sized nanotrack via homogeneous current injection. The authors use homogeneous current injection in a micrometer‑sized nanotrack and micromagnetic simulations of a granular, non‑uniform multilayer to study current‑induced skyrmion motion. Spin‑transfer torque drives the motion of the electrically generated sub‑100 nm skyrmions, and the study shows that an out‑of‑plane magnetic field stabilizes their motion while magnetic inhomogeneities significantly influence the dynamics.

Abstract

Magnetic skyrmions are nanoscale windings of the spin configuration that hold great promise for technology due to their topology-related properties and extremely reduced sizes. After the recent observation at room temperature of sub-100 nm skyrmions stabilized by interfacial chiral interaction in magnetic multilayers, several pending questions remain to be solved, notably about the means to nucleate individual compact skyrmions or the exact nature of their motion. In this study, a method leading to the formation of magnetic skyrmions in a micrometer-sized nanotrack using homogeneous current injection is evidenced. Spin-transfer-induced motion of these small electricalcurrent-generated skyrmions is then demonstrated and the role of the out-of-plane magnetic field in the stabilization of the moving skyrmions is also analysed. The results of these experimental observations of spin torque induced motion are compared to micromagnetic simulations reproducing a granular type, non-uniform magnetic multilayer, in order to address the particularly important role of the magnetic inhomogeneities on the current-induced motion of sub-100 nm skyrmions, for which the material grains size is comparable to the skyrmion diameter.