The tunable anisotropic Rashba spin-orbit coupling effect in Pb-adsorbed Janus monolayer WSeTe.

The spin-splitting properties of Pb-adsorbed monolayer Janus WSeTe are investigated based on first-principles calculations. The adsorbed system shows large Rashba splitting (the Rashba parameter is up to 0.75 eV Å), and we find that different adsorption layers (Te/Se adsorption layers) exhibit different significant features under spin-orbit coupling. Zeeman splitting and Rashba splitting co-exist at the high symmetry Γ point of the Te adsorption layer, while the Se adsorption layer exhibits anisotropic Rashba spin-orbit coupling. It was determined using k·p perturbation theory that Pb atom adsorption reduces the initial symmetry of the 2H-WSeTe monolayer and induces a strong spin-orbit coupling effect, so as to induce the anisotropic Rashba effect. Furthermore, the tunability of Rashba splitting was demonstrated by varying the adsorption concentration, adjusting the adsorption distance, and applying biaxial strain. This predicted adsorption system has potential value in spintronic devices.