on thulium iron garnets

Breaking time-reversal symmetry in topological insulators (TIs) via magnetic proximity effect attracted intense studies. The spin dynamics of magnetic insulators (MIs) interfacing with TIs has been investigated by ferromagnetic resonance,¹ and the magneto-transport of magnetized Bi₂Se₃ by MIs has been reported,² yet the crucial bulk-insulating TI, (Bi,Sb)₂Te₃ (BST) requires further thorough study. In this work properties of BST thin films deposited by molecular beam epitaxy on a-Al₂O₃ and tensile-strained Tm₃Fe₅O₁₂ (TmIG) of perpendicular magnetic anisotropy are reported. By adopting the low-temperature growth method,³ we demonstrated a significantly improved film growth evidenced by streaky reflection high-energy electron diffraction patterns attained at the first quintuple layer of BST on TmIG. TIs were confirmed bulk-insulating by electric transport and angle-resolved photoemission spectroscopy. We observed anomalous Hall effect up to 300K accompanied by suppressed weak anti-localization. Our work promotes the realization of quantum anomalous Hall effect at higher temperature and future TI-based devices.

1. Y. T. Fanchiang et al., Nat. Commun. 9, 223 (2018).
2. S. R. Yang et al., Phys. Rev. B 100, 045138 (2019).
3. C. C. Chen, et al., Appl. Phys. Lett. 114, 031601 (2019).