Robust Tunable Large-Gap Quantum Spin Hall States in Monolayer Cu2S on Insulating Substrates

Quantum spin Hall (QSH) insulators with large band gaps and dissipationless edge states are of both technological and scientific interest. Although numerous two-dimensional (2D) systems have been predicted to host the QSH phase, very few of them harbor large band gaps and retain their nontrivial band topology when they are deposited on substrates. Here, based on a first-principles analysis with hybrid functional calculations, we investigated the electronic and topological properties of inversion-asymmetric monolayer copper sulfide (Cu2S). Interestingly, we found that monolayer Cu2S possesses an intrinsic QSH phase, Rashba spin splitting, and a large band gap of 220 meV that is suitable for room-temperature applications. Most importantly, we constructed heterostructures of a Cu2S film on PtTe2, h-BN, and Cu(111) substrates and found that the topological properties remain preserved upon an interface with these substrates. Our findings suggest Cu2S as a possible platform to realize inversion-asymmetric QSH insulators with potential applications in low-dissipation electronic devices.

Automated summary

Based on first-principles calculations and hybrid functional analysis, this study reveals that the monolayer copper sulfide (Cu2S) possesses an intrinsic quantum spin Hall (QSH) phase, Rashba spin splitting, and a large band gap of 220 meV suitable for room-temperature applications. Heterostructures of Cu2S films on various substrates demonstrate the preserved topological properties. This suggests that Cu2S could serve as a platform for inversion-asymmetric QSH insulators with potential applications in low-dissipation electronic devices.