Tuning the magnetic anisotropy of La0.67Sr0.33MnO3 by CaTiO3 spacer layer on the platform of SrTiO3

Abstract

The control of perpendicular magnetic anisotropy(PMA) of complex oxides on the widely used SrTiO3 (STO) or STO buffered silicon substrates is of technology importance in the development of integrated multifunctional oxide spintronic devices. Perovskite manganite shows great potential as magnetic layer due to its rich physical properites and spin polarized character. However, when it is directly grown on the STO or STO buffered silicon substrates, the magnetization vector lies in the in-plane direction of the film, hindering its applications such as integrated spin orbital torque devices. In this work, we manipulate the PMA of the La0.67Sr0.33MO3 (LSMO) film by regulating its lattice deformation via CaTiO3 (CTO) spacer layer on the platform of STO. High crystal quality of the heterostructures with atomic sharp interfaces and elongation of LSMO lattice along c-axis were characterized. The vibration sample magnetometer (VSM) measurement indicates that the magnetic anisotropy of LMSO can be effectively tuned from in-plane to out-of-plane by inserting CTO between STO and LSMO. The improvement of PMA in LSMO films is also dependent on the thickness of the CTO spacer layer. Furthermore, the M-T curves imply that there are different magnetic phases in the LSMO films, including the appearance of antiferromagnetic phase. The analysis by electron energy loss spectroscopy (EELS) in scanning transmission electron microscopy mode found that the valence state of Mn near the CTO/LSMO interface is lower than the LSMO bulk phase, which could explained by a polar catastrophe model. This work provides a promising avenue to tailoring PMA of perovskite manganite and paves the way to realize integrated oxide spintronic devices on STO and STO buffered silicon platform.