Magnetic and structural properties of ultrathin epitaxial Fe3Si films on GaAs(001)

We have studied the thickness dependence of the structural and magnetic properties of ultrathin ${\mathrm{Fe}}_3\mathrm{Si}$ films grown on GaAs(001). The onset of ferromagnetism is found to be at about 3 ML at low temperatures. Furthermore, a reorientation of the uniaxial in-plane magnetic anisotropy takes place when the thickness of the films is reduced. This is due to a competition between a volume term and an interface contribution, which have opposite sign. Whereas the origin of the volume term remains unclear, the interface contribution is attributted to an anisotropic bonding at the ${\mathrm{Fe}}_3\mathrm{Si}∕\mathrm{Ga}\mathrm{As}\left(001\right)$ interface, similar to other ferromagnet/semiconductor hybrid structures.