24 February 2017 Temperature evolution of topological surface states in Bi2Se3 thin films studied using terahertz spectroscopy
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Abstract
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.
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Varun S. Kamboj, Varun S. Kamboj, Angadjit Singh, Angadjit Singh, Harvey E. Beere, Harvey E. Beere, Thorsten Hesjedal, Thorsten Hesjedal, Crispin H. W. Barnes, Crispin H. W. Barnes, David A. Ritchie, David A. Ritchie, } "Temperature evolution of topological surface states in Bi2Se3 thin films studied using terahertz spectroscopy", Proc. SPIE 10103, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X, 101030D (24 February 2017); doi: 10.1117/12.2249587; https://doi.org/10.1117/12.2249587
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