Extrinsic contributions to the ferromagnetic resonance response of ultrathin films

Abstract

We discuss the theory of extrinsic contributions to the linewidth of ultrathin ferromagnetic films, magnetized parallel to their surfaces. We invoke defect-induced two magnon scatterings, rendered active by unique aspects of dipolar contributions to spin wave dispersion in two dimensions. A two magnon shift in resonance frequency is present as well. We summarize our principal earlier conclusions, and present new results on the in-plane anisotropy of linewidth, for samples with stepped surfaces.