EAPSI: Investigating the Electronic Properties of Topological Insulator in the Presence of Magnetic Impurities

Pedramrazi Zahra, Berkeley CA

Investigators

Abstract

A topological insulator (TI) is a new phase of quantum matter. TIs are unique since they have insulating bulk as well as conducting edges. These edges transmit energy and information without loss, regardless of their length. These properties are very robust and the only way to change them is by introducing magnetic impurities. This project will fabricate a tunable system that can be changed from a metallic edge state to an insulating edge structure. The research will be conducted in collaboration with Professor Woong Yeom Han's group at Pohang University of Science and Technology in South Korea, one of the few groups in the world capable of fabricating and characterizing two-dimensional topological insulators. Hence, this collaboration provides a unique environment to characterize and fabricate a tunable topological insulating system. TIs are protected by time-reversal symmetry. This symmetry can withstand any defects and damage with the exception of magnetic impurities that break time-reversal symmetry. Therefore, to truly control the electronic properties of a topological insulator, one must understand its behavior in the presence of magnetic impurities. Although theoretical studies of two-dimensional TIs with magnetic defects have predicted that time-reversal breaking magnetic defects open a gap in the otherwise gapless edge state, there has been no experimental studies reported to verify this hypothesis. This project is focused on fabricating and characterizing a topological insulating Bi(111) bilayer on Bi2Te2Se in the presence of Kondo impurities using a scanning tunneling microscope (STM). This NSF EAPSI award is funded in collaboration with the National Research Foundation of Korea.