Spin waves theory in rare-earth films

Abstract A microscopic theory is presented for surface and bulk spin waves in films of rare-earth magnetic materials. The spin-wave spectrum has been calculated in the framework of the Heisenberg model including axial and hexagonal anisotropy. The spin-wave dispersion relations are obtained for several film thicknesses and different values of the ratio J 2 / J 1 . The dependence of the bulk band edges on the anisotropy and exchange parameters are also discussed. Numerical results are applied to Dysprosium below the temperature transition from the ferromagnetic phase to spiral spin arrangement.