In this work, we theoretically identify a phenomenon in which a slight rearrangement of atoms at a material's surface can veil its intrinsic topological character. Like donning a “quantum mask”, the surface presents a face different from the interior. This offers a clue toward resolving the long-standing debate, spanning nearly two decades, over the topology of bismuth. Our findings show that the long-held bulk-edge correspondence principle does not necessarily hold, opening a new path forward in understanding topological materials.
Fuseya et al. (Mon,) studied this question.