Theory of topological superconductivity and antiferromagnetic correlated insulators in twisted bilayer WSe2

Abstract

Abstract Since the very recent discovery of unconventional superconductivity in twisted WSe 2 homobilayers at filling ν  = − 1, considerable interest has arisen in revealing its mechanism. In this paper, we developed a three-band tight-binding model with non-trivial band topology by direct Wannierization of the low-energy continuum model. Incorporating both onsite Hubbard repulsion and next-nearest-neighbor attraction, we then performed a mean-field analysis of the microscopic model and obtained a phase diagram qualitatively consistent with the experiment results. For zero or weak displacement field, the ground state is a Chern number C  = ± 2 topological superconductor in the Altland-Zirnbauer A-class (breaking time-reversal but preserving total S z symmetry) with inter-valley pairing dominant in $${d}_{xy}\pm i{d}_{{x}^{2}-{y}^{2}}$$ d x y ± i d x 2 − y 2 –wave (mixing with a subdominant p x  ∓  i p y -wave) component. For a relatively strong displacement field, the ground state is a correlated insulator with the 120° antiferromagnetic order. Our results provide new insights into the nature of the twisted WSe 2 systems and suggest the need for further theoretical and experimental explorations.