MBE growth and STM study of thin-layer Bi₂Te₃ on two-dimensional magnetic Fe₃GeTe₂

Topological insulators with magnetic doping or proximity to magnetic materials can exhibit novel quantum effects such as quantum anomalous Hall effect (QAHE). The 2D magnetic Fe₃GeTe₂ has high ferromagnetic transition temperature, and if the topological insulator grown on its surface, magnetic proximity effect may be induced in the interface, which provides possibility to realize QAHE with higher critical temperature. In this work, we successfully grew 1-3 quintuple layer (QL) Bi₂Te₃ films on Fe₃GeTe₂ by molecular beam epitaxy (MBE), and observed moiré patterns (with a period of 4.8nm) by scanning tunneling microscopy (STM). On 1 QL Bi₂Te₃, we find the energy of Bi₂Te₃ quantum-well state changes periodically the moiré pattern, which is induced by periodic charge modulation of moiré pattern, and the change transfer at heterostructure interface. By means of quasi particle interference measurement, we find large energy gap opened at the Dirac cone of 1QL and 2QL Bi₂Te₃ island on Fe₃GeTe₂. This is consistent with our DFT calculation on the surface states of Bi₂Te₃/Fe₃GeTe₂ heterostructure. Finally, we also explored possible edge states of Bi2Te3 island, and find inversed-contrast for different type of edges. The fabrication of Bi₂Te₃/Fe₃GeTe₂ heterojunction provides a platform for realizing QAHE at higher temperature and further exploring topological superconductivity by growing superconducting film or islands on top.