Two-dimensional topological insulators with large bulk energy gap

Yang Z Q^{1, 2}, Jia Jin-Feng^{1, 2}, Qian Dong^{1, 2, †,}

Crystal and electronic structures of single-layer Bi₄Br₄, from Ref. [18]. (a) Unit cell of single-layer Bi₄Br₄. (b) Bulk electronic bands and the 1D edge state in Bi₄Br₄ nanoribbon. (c) Energy gap of single-layer Bi₄Br₄ as a function of external strain.