Fabrication and Characterization of the Moiré Surface State on a Topological Insulator

A Moiré superlattice on the topological insulator surface is predicted to exhibit many novel properties but has not been experimentally realized. Here, we developed a two-step growth method to successfully fabricate a topological insulator Sb₂Te₃ thin film with a Moiré superlattice, which is generated by a twist of the topmost layer via molecular beam epitaxy. The established Moiré topological surface state is characterized by scanning tunneling microscopy and spectroscopy. By application of a magnetic field, new features in Landau levels arise on the Moiré region compared to the pristine surface of Sb₂Te₃, which makes the system a promising platform for pursuing next-generation electronics. Notably, the growth method, which circumvents contamination and the induced interface defects in the manual fabrication method, can be widely applied to other van der Waals materials for fabricating Moiré superlattices.