Annealing influence on Co ultrathin film morphology in MBE grown Co/Au bilayers

A complex study in order to define optimal growth conditions for epitaxial Au/Co/Au sandwiches with a strong perpendicular magnetic anisotropy has been performed. The thermally induced evolution of the sandwich morphology, which deter-mines its magnetic properties, was studied by means of reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). The roughness of Au and Co surfaces, affected by the sample annealing, was evaluated from the length-dependent variance of topography acquired by atomic force microscopy (AFM). The vacuum annealing of an Au layer deposited on the Mo buffer improves significantly its morphology - a temperature of 170 degrees C is high enough to reduce the roughness more than twice. Gold acts as a surfactant appearing on the top of the Co layer after annealing at 250 degrees C.