300 Times Increased Diffusive Skyrmion Dynamics and Effective Pinning Reduction by Periodic Field Excitation

Thermally induced skyrmion dynamics as well as skyrmion pinning effects in thin films have attracted significant interest. While pinning poses challenges in deterministic skyrmion devices and slows down skyrmion diffusion, for applications in non-conventional computing, both pinning of an appropriate strength and skyrmion diffusion speed are key. Here, we employ periodic field excitations to realize an increase of the skyrmion diffusion by more than two orders of magnitude. Amplifying the excitation, we report a drastic reduction of the effective skyrmion pinning and observe a transition from pinning-dominated diffusive hopping to dynamics approaching free diffusion. By tailoring the field oscillation frequency and amplitude, we demonstrate continuous tuning of the effective pinning and skyrmion dynamics, which is a key asset and enabler for non-conventional computing applications. We find that the periodic excitations additionally allow us to stabilize skyrmions at different sizes for field values that are inaccessible in static systems, opening up new approaches to ultra-fast skyrmion motion by transiently exciting moving skyrmions.