Spin relaxation in ferromagnetic gadolinium

In this paper, we present experimental and theoretical results on ferromagnetic transmission resonance in gadolinium. A general, flexible theory of ferromagnetic transimission resonance including exchange, mixed boundary conditions and different types of relaxation is developed. The theory is applied to the experimental results obtained from several microns thick gadolinium foils at the temperatures 199, 252, and 273°K. The results indicate predominance of Bloch damping and of the Kittel boundary condition. The relaxation time is short of the order of ${10}^{-11\mathrm{}}$ sec and decreases with temperature. The transmission resonance results do not depend on any appreciable extent on the exchange stiffness constant.