Surface pinning effect of an antiferromagnetic interlayer exchange coupling in (Ga1−xMnxAs/GaAs:Be)10 multilayer

The depth-resolved magnetic configuration of a Ga 0.97 Mn 0.03 As/GaAs:Be multilayer with an antiferromagnetic interlayer exchange coupling was investigated using surface-sensitive soft x-ray resonant magnetic reflectivity (XRMR). We observed intriguing opposite increments in the XRMR intensities at the half-Bragg peak position between two different remanent states with opposite field sweep directions. A quantitative analysis shows that these opposite intensity increments result from two different anti-parallel spin configurations in such a way that the magnetization of top-most magnetic layer is pinned along the saturation magnetization direction before the remanent state. This surface pinning effect is important for understanding spin-dependent transport in semiconducting magnetic multilayers.