Perpendicular magnetic anisotropy in SrTiO3/Co/Pt films induced by oxygen diffusion from CaTiO3 spacer layer

Abstract

The control of perpendicular magnetic anisotropy (PMA) of magnetic metals on a platform of perovskite oxides, especially on widely used SrTiO3 substrates, is of technological importance in integrating conventional metal spintronic devices with multifunctional perovskite oxides. In this work, we tuned the magnetic anisotropy of Co/Pt on SrTiO3 (001) substrates by inserting an interfacial calcium titanate layer with an amorphous state. The crystallinity and device microstructure were characterized by transmission electron microscopy. The Hall effect and magnetic measurement show that the PMA was achieved with the inserting layer. The electronic structure analysis by x-ray photoelectron spectroscopy suggests that out-of-plane magnetic anisotropy corresponds to the appearance of a significant density of Co–O bonding and a reduction of the Ti valence state in the calcium titanate layer. It is indicated that the amorphous calcium titanate layer could serve as an effective oxygen source to modify the chemical environment of the interfacial Co and Ti, resulting in the tuning of hybridization between Co and oxygen as well as the magnetic anisotropy. This work paves the way to engineer the magnetic anisotropy of metallic spintronic devices on the platform of perovskite oxides via oxygen diffusion for possible application in multifunctional spin orbital torque memory devices.