Large area magnetic domain imaging of magnetite films with Spin‐SEM

Abstract

Abstract The surface crystallographic structure and magnetic structure of magnetite thin films epitaxially grown on a MgO(001) substrate were investigated by means of a scanning tunnelling microscope (STM), magnetic force microscope (MFM) and Spin‐polarized scanning electron microscopy (Spin‐SEM). The STM investigation and MFM measurement were performed in‐situ and in an ambient condition, respectively. After exposing the sample to air, a Spin‐SEM image was acquired. Spin‐dependent contrasted SEM images could be obtained after cleaning the sample surfaces. The cleaning procedure is annealing the sample at 250 °C in an ultra high vacuum (UHV) below 3 x 10–8 Pa for 3 hours. The STM observation indicates the thin films have antiphase domains and the observed MFM images reflect a cease in micromagnetic domain structures. Spin‐SEM images indicate that large‐scale magnetic inhomogeneity of a few μm is the inhomogeneity of the perpendicular magnetic moments of the films. Due to the spatial resolution limitation of our Spin‐SEM system, the correlation between the fine and coarse magnetic structures of the thin films induced by the antiphase domain boundaries is not clear, however, we have suggested the annealing process alone in a UHV makes the spin configuration of the thin films visible using a conventional Spin‐SEM system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)