Temperature evolution of topological surface states in bismuth selenide thin films studied using terahertz spectroscopy

Conference item

We have measured the terahertz (THz) conductance of a 23 quintuple layer thick film of bismuth selenide (Bi2Se3) and found signatures for topological surface states (TSSs) below 50 K. We provide evidence for a topological phase transition as a function of lattice temperature by optical means. In this work, we used THz time-domain spectroscopy (THz-TDS) to measure the optical conductance of Bi2Se3, revealing metallic behavior at temperatures below 50 K. We measure the THz conductance of Bi2Se3 as 10 e2/h at 4 K, indicative of a surface dominated response. Furthermore, the THz conductance spectra reveal characteristic features at ~1.9 THz attributed to the optical phonon mode, which is weakly visible at low temperatures but which becomes more prominent with increasing temperature. These results present a first look at the temperature-dependent behavior of TSSs in Bi2Se3 and the capability to selectively identify and address them using THz spectroscopy.

Authors: Kamboj, V; Singh, A; Beere, H; Hesjedal, T; Barnes, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: SPIE
• Host title: Proceedings of SPIE
• Journal: Proceedings of SPIE
• Volume: 10103D
• Issue: Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X
• Publication date: 2017-02-24
• Acceptance date: 2017-02-24
• Event location: San Francisco, California, United States
• DOI: 10.1117/12.2249587
• EISSN: 1996-756X
• ISSN: 0277-786X
• Keywords: bismuth selenide; spectroscopy; topological insulators; terahertz