Seminars Archive

Emergent honeycomb physics from chiral atomic orbitals on a triangular lattice

Domenico Di Sante
Dipartimento di Fisica, Università di Bologna

Abstract
In the hunt for room-temperature quantum spin Hall insulators, bismuthene [1] has demonstrated the impressive advantage of a local spin-orbit coupling experienced by the in-plane p-orbitals. This alternative to pi-bond graphene can be pushed to a conceptually even more essential level upon halving the honeycomb lattice, i.e. considering chiral p-orbitals on a triangular lattice. We theoretically conceive and experimentally realize for the first time a triangular real-space obstructed QSHI [2,3], "indenene", an indium monolayer exhibiting non-trivial valley physics and a large gap, as well as representing a model platform for higher-order topology [4]. We identify an interference mechanism of the Bloch functions and the emergence of a hidden honeycomb pattern in the charge localization, which makes the topological classification accessible to bulk experiments, without the necessity of quantum edge transport. [1] F. Reis et al, Science 357, 287 (2017) [2] M. Bauernfeind et al., Nat. Commun. 12, 5396 (2021) [3] P. Eck et al., Phys. Rev. B 106, 195143 (2022) [4] P. Eck et al., arXiv:2207.01359 (2022)