Angular distribution of magnetization in coated magnetic films

Abstract

Recent Möessbauer studies of magnetic films have described the orientational distribution of spins in terms of a mean angle of orientation between the spin direction and the direction of γ-ray propagation. These studies have improperly interpreted the quantity 〈sin2 θ〉, and have failed to account for the effects of saturation. We present an improved analysis which describes the spin orientational distribution in terms of an expansion in spherical harmonics. Coefficients in the expansion are determined from line intensities in the Zeeman-split spectra. A similar description, using the same distribution function, is applied to the angular dependence of the squareness of the hysteresis loop. Mössbauer results rely most heavily on the l=2 coefficients in the expansion. The magnetization, however, depends also on coefficients describing the characteristics of individual particles. Examples of the application of these techniques to films with different distributions of acicular particles are given.