Characterization of Fe₃O₄/GaAs(100) ultrathin films prepared by oxidizing kinetically-stabilized Fe layers

We examined the structural properties and the electronic and magnetic structures of an Fe₃O₄ ultrathin film prepared by oxidizing a low-temperature-grown (T = 95 K) Fe film on GaAs(100), using the X-ray diffraction, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism measurements. They show no clear contrast to those of an Fe ₃O₄ film that was prepared by oxidizing room-temperature-grown Fe film. The interdiffusions of Ga and As atoms in the Fe₃O₄ films were further investigated using the resonant Fe₃O₄(400) diffractions at the Ga K- and As K-edge energies. It is shown that the Fe₃O₄ film that originated from the room-temperature-grown Fe film contains both Ga and As atoms, while the film that originated from the kinetically-stabilized Fe film contains only Ga atoms. This suggests that the kinetic stabilization in pristine Fe layers can block As interdiffusion effectively even after oxidization.