Tight-binding model and quantum transport with disorder for 1T’ transition metal dichalcogenides

What is it about?

We present a simplified tight-binding (TB) model to describe the low-energy physics of monolayer 1T’ transition metal dichalcogenides (TMDCs). The TB model is constructed by combining symmetry analysis and first-principle calculations. Our TB model accurately reproduces the electronic structures near the Fermi energy and provides a better representation of energy band inversion. By considering spin–orbit coupling (SOC), our TB model successfully reproduces the opening of the bandgap, characterizes nontrivial topology, and predicts corresponding helical edge states. Additionally, using this TB model, we observe that quantized electronic conductance remains robust under significant disorder intensity. However, the robustness of the edge states can be suppressed by the Zeeman fields and SOC strength in the scattering zone. Furthermore, moderate concentrations of vacancy disorder destroy the topological protection and eliminate quantized conductance. Our TB model serves as a starting point for a comprehensive understanding of the properties of these materials and can guide future research on superconductivity, strain, and correlation effects.

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Photo by Chris Barker on Unsplash

Photo by Chris Barker on Unsplash

Why is it important?

1) We present a simplified TB model to describe the low-energy physics of monolayer 1T' transition metal dichalcogenides MX2, where M = (W, Mo) and X = (S, Te, Se); 2) Using this TB model, we observe that quantized electronic conductance remains robust under significant disorder intensity; 3) The robustness of the edge state can be suppressed by Zeeman fields and SOC strength in the scattering zone; 4) Moderate concentrations of vacancy disorder destroy the topological protection and eliminate quantized conductance.

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