QF Fellow and Associate seminar: Arman Rashidi

Tuning Displacement Fields in a Topological Insulator Using a Nanopatterned Gate

Arman is a postdoctoral scholar in the Stemmer group at UCSB. His research involves incorporating thin films of topological materials in nanoscale devices to probe/tune their topological physics and generate new phases of matter, all with the goal of creating device functionalities that can transform quantum computing technology. In this talk, Arman will present his work on tuning the displacement field in a topological insulator thin film using a nanopatterned gate. The electronic properties of topological materials are highly sensitive to the electric field applied across these materials. Controlling this electric field in thin films is, however, challenging. Here, I show that using a double-gated heterostructure in which one gate is nanopatterned, the displacement field across a quantum well of Cd3As2 is tuned. Transport studies in magnetic field show that with displacement fields as small as a 50 mV/nm a crossing of zeroth Landau levels turn into an anti-crossing, indictive of a topological phase transition. This work demonstrates a universal methodology for tuning electronic states in topological thin films.