Unconventional temperature evolution of quantum oscillations in Sn-doped Bi$_{1.1}$Sb$_{0.9}$Te$_{2}$S topological insulator

Bruno Gudac; Petar Sačer; Filip Orbanić; Ivan Kokanović; Zoran Rukelj; Petar Popčević; Luka Akšamović; Neven Ž. Barišić; Munisa Nurmamat; Akio Kimura; Mario Novak

arXiv · 2411.05207

Unconventional temperature evolution of quantum oscillations in Sn-doped Bi$_{1.1}$Sb$_{0.9}$Te$_{2}$S topological insulator

Bruno Gudac·Petar Sačer·Filip Orbanić·Ivan Kokanović·Zoran Rukelj·Petar Popčević·Luka Akšamović·Neven Ž. Barišić·Munisa Nurmamat·Akio Kimura·Mario Novak

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Abstract

Among various topological insulators, Sn-doped Bi$_{1.1}$Sb$_{0.9}$Te$_{2}$S 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.

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Bruno Gudac, Petar Sačer, Filip Orbanić, Ivan Kokanović, Zoran Rukelj, Petar Popčević, Luka Akšamović, Neven Ž. Barišić, Munisa Nurmamat, Akio Kimura, Mario Novak. 2024-11-07. Unconventional temperature evolution of quantum oscillations in Sn-doped Bi$_{1.1}$Sb$_{0.9}$Te$_{2}$S topological insulator. https://arxiv.org/abs/2411.05207

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