Observation of the surface hybridization gap in the electrical transport properties of the ultrathin topological insulator (Bi$_{1-x}$Sb$_{x}$)$_2$Te$_3$

Fuente: arXiv
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Auteurs principaux: van Veen, Feike, Kölling, Sofie, de Wit, Stijn R., Metsch, Roel, Rosenbach, Daniel, Li, Chuan, Brinkman, Alexander
Format: Preprint
Publié: 2025
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author van Veen, Feike
Kölling, Sofie
de Wit, Stijn R.
Metsch, Roel
Rosenbach, Daniel
Li, Chuan
Brinkman, Alexander
author_facet van Veen, Feike
Kölling, Sofie
de Wit, Stijn R.
Metsch, Roel
Rosenbach, Daniel
Li, Chuan
Brinkman, Alexander
contents We study the three-dimensional topological insulator (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ in its ultrathin limit i.e. when the thickness is of the same order as the surface state penetration depth. It is expected that in this limit a hybridization gap opens at the Dirac point, which gives rise to a quantum spin Hall (QSH) or insulating phase, depending on the material thickness. We fabricate (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ Hall bars with a thicknesses of 6 and 9 nm and measure an insulating phase around the Dirac point for low bias and at sub-Kelvin temperatures only in samples fabricated from the 6 nm films, which indicates the presence of a hybridization gap. The effect of a perpendicular magnetic field on the hybridization gap is studied but remains partially unresolved. The results form an important step towards experimentally realizing the quantum spin Hall state via hybridization in ultrathin films of (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$, yet, they also expose a knowledge gap regarding transport measurements in these systems.
format Preprint
id arxiv_https___arxiv_org_abs_2511_14454
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of the surface hybridization gap in the electrical transport properties of the ultrathin topological insulator (Bi$_{1-x}$Sb$_{x}$)$_2$Te$_3$
van Veen, Feike
Kölling, Sofie
de Wit, Stijn R.
Metsch, Roel
Rosenbach, Daniel
Li, Chuan
Brinkman, Alexander
Mesoscale and Nanoscale Physics
We study the three-dimensional topological insulator (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ in its ultrathin limit i.e. when the thickness is of the same order as the surface state penetration depth. It is expected that in this limit a hybridization gap opens at the Dirac point, which gives rise to a quantum spin Hall (QSH) or insulating phase, depending on the material thickness. We fabricate (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ Hall bars with a thicknesses of 6 and 9 nm and measure an insulating phase around the Dirac point for low bias and at sub-Kelvin temperatures only in samples fabricated from the 6 nm films, which indicates the presence of a hybridization gap. The effect of a perpendicular magnetic field on the hybridization gap is studied but remains partially unresolved. The results form an important step towards experimentally realizing the quantum spin Hall state via hybridization in ultrathin films of (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$, yet, they also expose a knowledge gap regarding transport measurements in these systems.
title Observation of the surface hybridization gap in the electrical transport properties of the ultrathin topological insulator (Bi$_{1-x}$Sb$_{x}$)$_2$Te$_3$
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2511.14454