Molecular Beam Epitaxy Grown Cr2Te3 Thin Films with Tunable Curie Temperatures for Spintronic Devices

Materials that have a perpendicular magnetic anisotropy (PMA) effect with a high Curie temperature are essential in spintronics applications. Cr2Te3 is a transition-metal chalcogenide that demonstrates a PMA effect but with a relatively low Curie temperature of about 180 K, significantly limiting its practical application. In this work, we reported the epitaxial growth of Cr2Te3 thin films on Al2O3 substrates with a Curie temperature ranging from 165 to 295 K, closely dependent on the thicknesses and lattice constants of the thin films. To study the physical origin of the improved Curie temperature, structural analysis, magneto-transport, and magnetic characterizations were conducted and analyzed in detail. In contrast with previous reports, all the high Curie temperature thin films have electron type carriers instead of hole carriers, which is possibly caused by the Al diffusion from the Al2O3 substrate. On the basis of the structure and chemical analysis, a phenomenological model based on the degree of coupling between ferromagnetic and antiferromagnetic ordering, hosted by the fully occupied and with-vacancy Cr layer alternatively, was proposed to explain the observed Currie temperature enhancement in our samples. These findings indicate that the Curie temperature of Cr2Te3 thin films may potentially be tuned by Al doping, performing as a novel magnetic material suitable for various magnetic applications.