One-dimensional physics in the edge states of the high-temperature quantum spin Hall system bismuthene on SiC(0001)*

Bismuthene (a mono-atomic honeycomb lattice of Bi-atoms) chemisorbed on a SiC(0001) substrate has recently been synthesized and shown to be a promising candidate for the realization of a room-temperature Quantum Spin Hall (QSH) effect which is based on a novel QSH mechanism [1]. Experiments with angle-resolved photoelectron spectroscopy (ARPES) and scanning tunneling microscopy (STM) found excellent agreement with the calculated topological band structure. In particular, while the bismuthene film displays a large bulk band gap of ~0.8 eV, conducting edge states are observed at the boundaries of the honeycomb layer, e.g. at terrace steps of the substrate, as expected for a two-dimensional topological insulator. Here we demonstrate, by a detailed analysis of tunneling spectra, that these edge states are indeed one-dimensional (1D) and correlated in nature. The spectra display power law behavior with energy and temperature as well as universal scaling, consistent with the expectations for tunneling into a Tomonaga-Luttinger liquid and in excellent agreement with experimental observations in other 1D systems.

[1] F. Reis et al., Science 357, 287 (2017)