Two magnon scattering in ultrathin ferromagnets: The case where the magnetization is out of plane

Abstract

We extend our earlier treatment of two magnon scattering in ultrathin ferromagnets to the case where the magnetization is tipped out of plane by virtue of the application of an out of plane magnetic field. The general formalism developed earlier is generalized in this regard, so when the magnetization is canted out of plane, one may extract information on the two magnon contribution to the linewidth or on the frequency shift of the ferromagnetic resonance line with origin in two magnon scattering. We provide the full set of response functions for such a film, which describe its response to driving fields of finite wave vector, so one may also explore two magnon effects on Brillouin light scattering if desired. We present explicit calculations that illustrate the behavior of the ferromagnetic resonance linewidth, for the picture employed earlier, where surface or interface defects activate two magnon scattering.