Coherent Microwave Driving of Domain Wall Depinning in a Ferrimagnetic Garnet.

Abstract

Coherent control of domain wall dynamics offers a route to the fast manipulation of magnetic textures beyond thermally activated motion. We demonstrate the resonant excitation of linear and nonlinear dynamics of a pinned domain wall in a ferrimagnetic garnet thin film driven by a microwave field. Using scanning nitrogen-vacancy magnetometry and nonlocal spin-pumping measurements, we identify a low-frequency mode inside the magnon gap originating from the localized oscillatory motion of a domain wall across a pinning line defined by a Pt stripline. Upon an increase in the microwave drive into the nonlinear regime, this mode enables domain wall depinning at reduced external magnetic fields. Micromagnetic simulations reveal a progression from localized oscillations to partial relocation between pinning sites and ultimately complete escape from the pinning region with increasing driving power. These results establish the resonant excitation of domain walls at engineered pinning sites as a mechanism for manipulating magnetic textures via localized nonlinear dynamics.