Direct visualization of dynamic magnetic coupling in a Co/Py bilayer with picosecond and nanometer resolution

Abstract

We present a combination of ferromagnetic resonance (FMR) with spatially and time-resolved X-ray absorption spectroscopy in a scanning transmission X-ray microscope (STXM-FMR). The transverse high frequency component of the resonantly excited magnetization is measured with element-specifity in a Permalloy (Py) disk - Cobalt (Co) stripe bilayer microstructure. STXM-FMR mappings are snapshots of the local magnetization-precession with nm spatial resolution and ps temporal resolution. We directly observe the transfer of angular momentum from Py to Co and vice versa at their respective element-specific resonances. A third resonance could be observed in our experiments, which is identified as a coupled resonance of Py and Co.Comment: Version submitted to Physical Review Applied with updated author list and supplemental information (Ancillary file