EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Wafer scale 2D ferromagnetic materials CrxTey [1] and Fe3GeTe2 (FGT) [2] are epitaxially grown by molecular beam epitaxy on InAs /Si and insulating MoS2/sapphire substrates. In situ STM and XRD experiments reveal that CrxTey are compatible with Cr2Te3 and Cr5Te8 compositions although a clear distinction between these phases cannot be made. The FGT composition is verified by Raman and EDX. Magnetic properties are probed by SQUID and, in the case of materials grown on insulating substrates, by Anomalous Hall Effect measurements. Both ferromagnetic materials show strong perpendicular magnetic anisotropy at Curie temperatures Tc typically lower than 250 K. The Tc, the saturation magnetization Ms and the coercivity of CrxTey show a strong dependence on growth temperature Tg. High Tg ~ 400 C results in a mixture of magnetic phases one of which has very low coercivity. On the other hand, at low Tg ~225 C, optimum single phase CrxTey is obtained with the largest Ms ~ 50 emu/cm3 and the largest coercivity of ~ 0.8 T at 10K, which makes it suitable for low temperature spin-orbit torque (SOT) experiments. MBE grown thin CrxTy or FGT samples prepared with bottom or top Bi2Te3 and SnBi2Te4 [3] topological insulators have been successfully achieved making them a perfect tool to probe surface states Edelstein conversion from top or bottom TI surface.
Acknowledgements: H2020 FETPROAC-SKYTOP-824123; FLAG-ERA MELoDICA; HFRI No 435 2D-TOP
[1] H. Li et al., ACS Appl. Nanomaterials DOI: 101021/acsnm 9b01179 (2019)
[2] H. Wang et al., ACS Nano 14, 10045 (2020)
[3] S. Fragkos et al., Phys. Rev. Materials 5, 014203 (2021)