SPIN-DIFFUSION IN 2D XY FERROMAGNET WITH DIPOLAR INTERACTION

In the ordered phase of 2D XY ferromagnet, the dipole force induces st rong interaction between spin waves in the long-wave limit. This inter action leads to transformation of the spin-wave excitation into a new soft mode in an intermediate range of wave vectors, limited in magnitu de and direction, and into an anomalous anisotropic diffusion mode at long wavelengths. The dissipation of spin waves at short wavelengths i s found to be highly anisotropic.