Eddy currents and spin excitations in conducting ferromagnetic films

We explore the influence of the finite conductivity on spin waves in metallic ferromagnetic films. We consider propagation perpendicular to the magnetization, which is parallel to the surface, and wavelengths sufficiently long that the influence of exchange may be ignored. Precession of the magnetization induces eddy currents which damp the spin waves, and also renormalize the dispersion relation of the Damon-Eshbach mode encountered in this geometry. We provide analytic formulas which describe these effects, in various limits. Studies through use of a Green's-function method explore the influence of the conductivity on the spectrum of spin fluctuations, in various wavelength regimes.