Exploring Electron Transport in Magnetic Topological Insulators

Abstract

Topological Insulators are an entirely new state of matter found in semiconductors. Such solids are characterized by an insulating bulk surrounded by conducting surfaces. Conduction on the surface is non-dissipative and spin polarized. In reality, however, atomic and structural defects dope the material with charge carriers that allow charges to flow through the bulk. This makes the surface states difficult to probe. Doping with magnetic ions has also been shown to suppress the surface states. We present results on magnetic and non-magnetic topological insulator thin films grown by molecular beam epitaxy. Electrical transport measurements suggest possible evidence of surface contributions to the magnetoresistance. This is achieved by comparing measurements made on magnetic and non-magnetic samples. We also explore the magnetism present in our samples by making low temperature SQUID magnetometry measurements as well as anomalous Hall measurements.