Three distinct topological degrees of freedom are used to define all topological spin textures based on out-of-plane and in-plane spin configurations: the topological charge, representing the number of times the magnetization vector m wraps around the unit sphere; the vorticity, which quantifies the angular integration of the magnetic moment along the circumferential direction of a domain wall; and the helicity, defining the swirling direction of in-plane magnetization.
Electrical manipulation of these three degrees of freedom has garnered significant attention due to their potential applications in future spintronic devices. Among these, the helicity of a magnetic skyrmion—a critical topological property—is typically determined by the Dzyaloshinskii-Moriya interaction (DMI). However, controlling skyrmion helicity remains a formidable challenge.
A team of scientists led by Professor Yan Zhou from The Chinese University of Hong Kong, Shenzhen, and Professor Senfu Zhang from Lanzhou University successfully demonstrated a controllable helicity switching of skyrmions using spin-orbit torque, enhanced by thermal effects.
