Influence of ripple and skew on the fall-back angle α₅₀ in thin uniaxial permalloy films

Abstract

The overall fall-back angle α₅₀ of thin uniaxial ferromagnetic films was calculated including the effect of the magnetization ripple and the skew. Both, ripple and skew angle were assumed to show a Gaussian distribution with different standard deviations. Ripple and skew are superimposed in a nonlinear manner to give the fall-back angle of the entire film. By direct measurements of the ripple fall-back angle, α ⁰₅₀ , for very small spots of the film, of the fall-back angle, α₅₀, of the entire film, and of the distribution and standard deviation of the skew, the calculation could be tested, which gave good agreement between experiment and theory. As long as the skew is unknown the fall-back angle alone is not the best measure for the “quality” of an uniaxial film.