Canted Spin Texture and Quantum Spin Hall Effect in WTe₂

We report an unconventional quantum spin Hall phase in the monolayer Td-WTe₂, which exhibits hitherto unknown features in other topological materials. The low-symmetry of the structure in-duces a canted spin texture in theyzplane, which dictates the spin polarization of topologically protected boundary states. Additionally, the spin Hall conductivity gets quantized (2e²/h) witha spin quantization axis parallel to the canting direction. These findings are based on large-scale quantum simulations of the spin Hall conductivity tensor and nonlocal resistances in multi-probe geometries using a realistic tight-binding model elaborated from first-principle methods. The observation of this canted quantum spin Hall effect, related to the formation of topological edge stateswith nontrivial spin polarization, demands for specific experimental design and suggests interestingalternatives for manipulating spin information in topological materials.