Shubnikov-De Haas oscillation in 3D topological insulator Bi₂ Se₃ nano-flakes

Abstract

The Shubnikov-De Haas (SdH) oscillation phenomena of topological insulator Bi₂Se₃ have been investigated in this thesis. The temperature-dependent magnetoresistance (MR) and magnetic field direction dependent MR are systematically studied both in the n type and p type Bi₂Se₃ nano-flake samples. For both n type and p type Bi₂Se₃ samples, the SdH oscillations only respond to the component of the magnetic field perpendicular to the sample surface, indicating the oscillation has a 2D nature. Furthermore, with analysis of the Landau level fan diagram, a π-Berry phase of these 2D electrons is detected, suggesting the SdH oscillation originates from the topological surface states instead of the bulk state. Moreover, the temperature-dependent SdH amplitude studies further provide several important parameters of the surface electrons such as the cyclotron effective mass, Dingle time, Dingle temperature, and mobility. A comparison of these parameters of n type and p type samples is further provided. Moreover, our results obtained from the SdH oscillation measurement are in good agreement with the well-known ARPES results of Bi₂Se₃ surface states. Our electrical transport measurements of n type and p type Bi₂Se₃ sample show that the SdH oscillation can be a good method for probing the topological surface state of 3D topological insulator.

Date of Award	2014
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology