Author(s): Lou, WK (Lou, Wen-Kai); Yang, W (Yang, Wen); Chang, K (Chang, Kai)

Source: PHYSICAL REVIEW B Volume: 105 Issue: 4 Article Number: 045305 DOI: 10.1103/PhysRevB.105.045305 Published: JAN 18 2022

Abstract: Band inversion accompanied by the emergence of gapless and helical edge states at the boundary is a hallmark of 2D topological insulators. However, a recent experiment reports the existence of edge states before band inversion in InAs/GaSb quantum wells [F. Nichele et al., New J. Phys. 18, 083005 (2016)]. The underlying physics remains an open problem. Here we provide a possible solution by showing that helical edge states emerge before band inversion as long as the bulk gap falls below a positive threshold determined by the particle-hole asymmetry and interband coupling. In the presence of quantum confinement or local electrostatic potential near the boundary, these edge states may enter the gap of bulk states and be detected as edge conductance in transport measurements. Our work reveals the possible existence of the helical conducting edge states in a large class of narrow-gap semiconductors.

Accession Number: WOS:000766689000010

Author Identifiers:

Author Web of Science ResearcherID ORCID Number

Lou, Wen-Kai D-2105-2015 0000-0001-6906-6479

ISSN: 2469-9950

eISSN: 2469-9969

Full Text: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.045305