Two-magnon scattering in a self-assembled nanoscale network of misfit dislocations

The static and dynamic properties of magnetic Pd/Fe(001) ultrathin film crystalline structures prepared on GaAs(001) templates were investigated by ferromagnetic resonance (FMR) from 10 to 73 GHz. It will be shown that the formation of a self-assembled nanoscale network of misfit dislocations in crystalline structures can be detected during the growth by fan-out diffraction features in reflection high electron energy diffraction. This network of defects leads to a strong extrinsic magnetic damping. The out-of-plane measurements of the FMR linewidth have revealed that the extrinsic damping is caused by two-magnon scattering. The contribution to the FMR linewidth from two-magnon scattering is strongly anisotropic and follows the rectangular symmetry of the glide planes of the misfit dislocation network. It will be shown that the observed strong anisotropy in two-magnon scattering can be interpreted by Fourier components of magnetic defects. The angular dependence of the Fourier components results in an effective channelling of scattered spin waves.