Controlling the magnetic properties of layered Cr2Te3 thin films via ex-situ annealing

We present a post-growth ex-situ annealing method to control the Curie temperature and magnetic anisotropy of Cr2Te3 van der Waals ferromagnetic thin films. The as-grown Cr2Te3 films exhibit a Curie temperature -170 K with an out-of-plane magnetic easy axis. Upon high temperature (300 - 400 degrees C) ex-situ annealing, the magnetic phase of the film changes: the Curie temperature is significantly increased to -300 K and the magnetic easy axis is reoriented to the in-plane direction. Electronic, chemical, and structural analyses suggest that the c-axis lattice constant expansion, accompanying the annealing process, is the origin of the ex-situ-annealing-induced modu-lation of the Cr2Te3 film magnetic properties. These results demonstrate that a practical ex-situ annealing process can be effectively used to control the magnetic properties of van der Waals ferromagnetic thin films. Further-more, the room temperature ferromagnetic ordering emerging upon annealing, along with its robustness against post-growth thermal processes, suggests that the Cr2Te3 thin film is a promising magnetic material candidate for potential application in van-der-Waals-material-based spintronic devices.