Dissipationless edge transport in single-layer topological insulator Bi₄Br₄ based device under high vacancy concentration

Single-layer Bismuth Monobromide (SL-Bi₄Br₄) is a recently experimentally confirmed room temperature quantum spin hall insulator with a relatively large bulk band gap. In this paper, we investigate the electronic properties of SL-Bi₄Br₄and single-layer bismuth monobromide nanoribbon (SL-Bi₄Br₄NR) introducing different vacancy defects near the nanoribbon edges. With maximally localized wannier function (MLWF) constructed Hamiltonian we show that SL-Bi₄Br₄NR edge states are protected by bulk topology and robust against disorder. In conjunction with MLWF and non-equilibrium Green's function, we also show that in devices made from SL-Bi₄Br₄, transmission through the topologically protected edge states do not suffer from degradation when the device is sufficiently wide. Increasing channel length and defect concentration affect only the bulk states transmission leaving edge states transmission perfectly quantized. This resilience against disorder signifies SL-Bi₄Br₄'s promising candidacy for next-generation electronic & spintronics devices application.