Magnetization states in ultrathin films with laterally modulated anisotropies

Abstract

Micromagnetic theory has been applied to a model system for ultrathin films with laterally modulated anisotropies, consisting of a periodic array of stripes with alternating uniaxial anisotropies. Despite of the discontinuous change of anisotropy, the magnetization direction only changes on a lateral scale given by the exchange length. If the width of one of the two alternating stripes is reduced below a critical value, the magnetization will switch into a uniform state. The variation of the critical width with period, anisotropy constants, exchange constant, and film thickness has been determined using an analytic approach. Non-uniform magnetization states and the magnetization reversal in an external field have been determined using numerical calculations. The results are compared with experimental results for Fe/W(1 1 0)-films.