Ultrasensitive Sub-monolayer Palladium Induced Chirality Switching and Topological Evolution of Skyrmions

TL;DR

This paper demonstrates ultrasensitive control of skyrmion chirality and topological properties in multilayer films through minimal Pd capping, revealing potential for low-energy skyrmionic device applications.

Contribution

It introduces a method to switch skyrmion chirality using only 0.22 monolayer of Pd, showing detailed evolution of domain walls and skyrmions with minimal energy cost.

Findings

Chirality of domain walls switches from left- to right-handed with Pd capping.

Skyrmion topological protection diminishes during chirality switching.

Energy cost of chirality switching is less than 1 attojoule.

Abstract

Chiral spin textures are fundamentally interesting, with promise for device applications. Stabilizing chirality is conventionally achieved by introducing Dzyaloshinskii-Moriya interaction (DMI) in asymmetric multilayers where the thickness of each layer is at least a few monolayers. Here we report an ultrasensitive chirality switching in (Ni/Co)n multilayer induced by capping with only 0.22 monolayer of Pd. Using spin-polarized low-energy electron microscopy, we monitor the gradual evolution of domain walls from left-handed to right-handed Neel walls and quantify the DMI induced by the Pd capping layer. We also observe the chiral evolution of a skyrmion during the DMI switching, where no significant topological protection is found as the skyrmion winding number varies. This corresponds to a minimum energy cost of < 1 attojoule during the skyrmion chirality switching. Our results demonstrate the detailed chirality evolution within skyrmions during the DMI sign switching, which is relevant to practical applications of skyrmionic devices.