Spin-polarized conducting edge currents counterpropagate in quantum spin Hall (QSH) insulators and are protected against disorder-driven localizations by the time-reversal symmetry. Using these spin-currents for device applications require materials having large band gap and fast switchable QSH states. By means of in-depth first-principles calculations, we demonstrate the large band gap and fast switchable QSH state in a newly introduced two-dimensional (2D) material family with 1T′-MGe2Z4 (M = Mo or W and Z = P or As). The thermodynamically stable 1T′-MoGe2Z4 monolayers have a large energy gap around ∼237 meV. These materials undergo a phase transition from a QSH insulator to a trivial insulator with a Rashba-like spin splitting under the influence of an out-of-plane electric field, demonstrating the tunability of the band gap and its band topology. Fast topological phase switching in a large gap 1T′-MoGe2Z4 QSH insulators has potential applications in low-power devices, quantum computation, and quantum communication.
@article{arxiv.2211.06443,
title = {Fast electrically switchable large gap quantum spin Hall states in MGe$_2$Z$_4$},
author = {Rajibul Islam and Ghulam Hussain and Rahul Verma and Mohammad Sadegh Talezadehlari and Zahir Muhammad and Bahadur Singh and Carmine Autieri},
journal= {arXiv preprint arXiv:2211.06443},
year = {2023}
}