2024/11/07 by Bruno Gudac, Petar Sačer, Gudac, Bruno +19 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #FOS: Physical sciences #High-pressure geophysics and materials #Materials Science (cond-mat.mtrl-sci) #Photorefractive and Nonlinear Optics #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2411.05207
openalex publication_date 2024/11/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Among various topological insulators, Sn-doped Bi1.1Sb0.9Te2S stands out for its exceptional properties. It has a wide energy gap and typically exhibits a well-isolated Dirac point and a Fermi level positioned within the gap. The samples we present display metallic-like low-temperature resistivity attributed to surface states, pronounced quantum oscillations observable even at 40 K, and a Fermi level located approximately 100 meV above the Dirac point. In this work, we report an unusual effect: a strong temperature dependence of the quantum oscillation frequency, which decreases by around 10% between 2 and 40 K. This reduction significantly exceeds the expected effects of the Sommerfeld and topological corrections for Dirac quasi-particles, which could account for only one-eighth of the observed change. We attribute this change to the temperature-induced renormalization of the bulk band gap size due to electron-phonon interactions, which in turn affect the position of the surface Dirac point within the gap. Furthermore, we propose that in this compound, surface quantum oscillations can serve as a precise tool for investigating the low-temperature evolution of the bulk band gap size.