Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 74: Topological Insulators
TT 74.6: Talk
Thursday, March 12, 2026, 10:45–11:00, CHE/0091
THz Signatures of Boundary-Dominated Transport in Bi2TeI — •shuhan wang1, Anjan N M1, Mohammad Mehmandous2, Michael Ruck2, and Stefan Kaiser1 — 1Institute of Solid State and Materials Physic, TUD Dresden University of Technology — 2Inorganic Chemistry II,TUD Dresden University of Technology
Bi2TeI is a weak topological insulator made of stacked topologically nontrivial (QSH) layers separated by trivial insulating layers. Despite its weak topological indices, it still hosts symmetry-protected boundary states on specific crystal surfaces. Using terahertz time-domain spectroscopy (THz-TDS), we resolve its low-energy electrodynamics in thin films. The THz conductivity shows a low frequency Drude response dip at 15K-20 K. This behavior is consistent with dc transport measurements. Notably, these features are only seen in thin films which are absent in bulk crystals. The suppression of Drude weight points to a crossover toward boundary-dominated transport in Bi-TeI thin films.
Keywords: weak topological insulator; THz spectroscopy; THz conductivity