The growth and magnetic properties of epitaxial magnetite Fe3O4 on GaAs(100) have been studied by reflection high-energy electron diffraction, x-ray photoelectron spectroscopy, magneto-optical Kerr effect, and x-ray magnetic circular dichroism. The epitaxial Fe3O4 films were synthesized by in situ post growth annealing of ultrathin epitaxial Fe films at 500K in an oxygen partial pressure of 5×10−5mbar. The XMCD measurements show characteristic contributions from different sites of the ferrimagnetic magnetite unit cell, namely, Fetd3+, Feoh2+, and Feoh3+. The epitaxial relationship was found to be Fe3O4(100)⟨011⟩∕∕GaAs(100)⟨010⟩ with the unit cell of Fe3O4 rotated by 45° to match that of GaAs(100) substrate. The films show a uniaxial magnetic anisotropy in a thickness range of about 2.0–6.0nm with the easy axes along the  direction of the GaAs(100) substrate.
Lu, Y. X., Claydon, J. S., Xu, Y. B., Thompson, S. M., Wilson, K., & van der Laan, G. (2004). Epitaxial growth and magnetic properties of half-metallic Fe3O4 on GaAs(100). Physical Review B, 70(23), . https://doi.org/10.1103/PhysRevB.70.233304