The nature of charged zig-zag domains in MnAs thin films

We report on apparently charged domain walls in MnAs-on-GaAs(0 0 1) layers. For head-on domains, described as two domains facing each other with opposite magnetization, the domain walls of ≳ 200 nm thick films exhibit a zig-zag pattern. Depending on the width of the ferromagnetic stripes, which is a function of temperature and thus the strain in the easy axis direction, the zig-zag angle 2 θ increases from 90^{{ring operator}} in the case of wide stripes to 180^{{ring operator}} (i.e., to a straight wall) for narrow stripes. The underlying domain structure was calculated using a three-dimensional micromagnetic simulator. The calculations reveal a number of distinct domain patterns as a result of the system's attempt to reduce its energy through the formation of closure domain-like patterns in the easy plane. A diamond-like state consisting of two intersecting sub-surface domain walls is the underlying magnetic structure resulting in the observed, apparently charged domain walls. The zig-zag pattern of the domain boundary is explained by stray field minimization of the diamond state along the stripe.