Nanofabrication and Transport Studies of Quasi-one-dimensional Topological Insulators Bismuth Halogenides

Bismuth Halogenides Bi₄X₄ (X = Br, I) is a family of quasi-one-dimensional (1D) topological insulators (TIs) which promise advantages such as multiple cleavage planes, strain-induced phase transitions and hosting of helical hinge modes. Recent scanning tunneling microscope (STM) and angle-resolved photoemission spectroscopy (ARPES) studies show that Bi₄Br₄ has gapless monolayer step edge and a large bulk gap (~0.2meV) which indicates that it is a promising quantum spin Hall insulator (QSHI) up to room temperature. We are able to exfoliate and fabricate hexagonal boron nitride incapsulated thin layer Bi₄Br₄ field-effect transistors. In this talk, we will discuss latest transport data as functions of magnetic field and temperature.