Topological Electronic Structures of Quasi-one-dimensional Bismuth Halides Investigated by Angle-resolved Photoemission Spectroscopy

Abstract

Quasi-one-dimensional materials offer an ideal playground to investigate weak topological insulators (WTIs) and higher-order topological insulators (HOTIs), since their characteristic boundary states emerge in the naturally cleaved surfaces. Utilizing laser-based angle-resolved photoemission spectroscopy (ARPES) and synchrotron-based nano-ARPES, we show evidence of a WTI phase in β-Bi4I4 and a HOTI phase in Bi4Br4.