Magnetization reorientation induced by interfacial structures in ultrathin disordered FePt film sandwiched by SiO2 layers

In general, ultrathin disordered FePt film exhibits in-plane magnetic anisotropy due to large demagnetization fields and negligible volume anisotropy. Here, we demonstrated that magnetization reorientation from in-plane to out-of-plane takes place when ultrathin disordered FePt film is sandwiched by amorphous SiO2 layers and annealed at 350 °C. Based on the interfacial and structural analysis from X-ray photoelectron spectroscopy and high resolution transmission electron microscopy, the reorientation originates from the electronic structural changes because of strong bonding between Fe and O atoms at the top FePt/SiO2 interface. This interface anisotropy plays a crucial role in the magnetic behaviour, resulting in magnetization reorientation of ultrathin disordered FePt film.