Probing the Topological Surface State in Bi2Se3Thin Films Using Temperature-Dependent Terahertz Spectroscopy

• DOI: 10.1021/acsphotonics.7b00492
• Publication Date: 2017-09-27T18:57:56Z
• Authors: Varun S. Kamboj; Angadjit Singh; Thierry Ferrus; Harvey E. Beere; Liam B. Duffy; Thorsten Hesjedal; Crispin H. W. Barnes; David A. Ritchie
• Keywords: Topological insulator; Surface States

Strong spin–momentum coupling in topological insulators gives rise to surface states, protected against disorder scattering by time reversal symmetry. The study of these exotic quantum states not only provides an opportunity explore fundamental phenomenon condensed matter physics, such as the spin Hall effect, but also lays foundation for applications computing spintronics. Conventional electrical measurements suffer from substantial bulk interference, making it difficult clearly identify state bulk. We use terahertz time-domain spectroscopy temperature-dependent optical behavior a 23-quintuple-thick film bismuth selenide (Bi2Se3), allowing deconvolution response signatures at low temperatures (<30 K) with conductance Bi2Se3 exhibiting metallic are observed. Measurement carrier dynamics results mobility exceeding 2000 cm2/V·s 4 K, indicative surface-dominated response. A lifetime ∼0.18 ps and density 6 × 1012 cm–2 K were obtained measurement. spectra reveal characteristic features ∼1.9 THz, attributed phonon mode, which becomes less prominent falling temperature. transport weak antilocalization our sample, consistent presence state.