Emerging Nontrivial Topology in Ultrathin Films of Rare-Earth Pnictides

Published

October 23, 2023

Author(s)

Dai Ho, Ruiqi Hu, Quang To, Garnett Bryant, Anderson Janotti

Abstract

Thin films of semimetals, such as rare-earth monopnictides, are expected to turn into semiconductors due to quantum confinement effect, which lifts the overlap between electron pockets at Brillouin zone edges and hole pockets at the zone center. Instead, taking non-magnetic LaSb as an example, we find the emergence of a quantum spin Hall insulating phase in LaSb(001) films as the thickness is reduced to 7, 5, or 3 monolayers. This is attributed to a strong quantum confinement effect on the in-plane electron pockets, and the lack of quantum confinement on the out-of-plane pocket in reciprocal space projected onto zone center, leading to a band inversion. Spin-orbit coupling opens a sizeable non-trivial gap in the band structure of the thin films. Such effect is shown to be general in rare-earth monopnictides and may lead to interesting phenomena when coupled with the 4f magnetic moments present in other members of this material family.

Citation

ACS Nano

Volume

17

Issue

21

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acsnano.3c03307

Local Download

Keywords

quantum spin Hall insulator, semi-metals, rare-earth monopnictides, quantum confinement, spin-orbit coupling, thin films

Citation

Ho, D. , Hu, R. , To, Q. , Bryant, G. and Janotti, A. (2023), Emerging Nontrivial Topology in Ultrathin Films of Rare-Earth Pnictides, ACS Nano, [online], https://doi.org/10.1021/acsnano.3c03307, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936253 (Accessed October 14, 2025)