Superconducting diode effect in 1T’-WS₂/2H-WS₂ heterophase bilayer

The nonreciprocity of the superconducting critical current is known as the superconducting diode effect, which can be realized in noncentrosymmetric superconductors with broken time reversal symmetry. Using density functional theory, we propose a new system, the 1T’-WS₂/2H-WS₂ heterophase bilayer, that exhibits the superconducting diode effect. We find that the electron doping from the 2H-WS₂ layer to the 1T’-WS₂ layer creates an interface dipole and induces Rashba band splitting. This results in the formation of finite momentum Cooper pairs under an in-plane magnetic field that lead to nonreciprocity of critical current. Using ab initio Migdal–Eliashberg theory, we confirm the superconductivity in this heterophase bilayer. We also found that the critical temperature of the heterophase bilayer depends on the strain and the amount of charge transfer. Our work demonstrates that by exploring different combinations of TMDC materials and phases, one can achieve novel topological superconducting properties in van der Waals heterostructures of 2D materials.