Nematic, chiral, and topological superconductivity in twisted transition metal dichalcogenides

We introduce and study a realistic model for superconductivity in twisted bilayer ${\mathrm{WSe}}_2$, where electron pairing arises from spin-valley fluctuations in the weak-coupling regime. Our model comprises both the full continuum model moiré band structure and a short-ranged repulsive interaction. By calculating the spin-valley susceptibility, we identify a significant enhancement of the spin-valley fluctuations near half filling of the topmost moiré band. We then analyze the dominant Kohn-Luttinger pairing instabilities due to these spin-valley fluctuations and show that the leading instability corresponds to a two-component order parameter, which can give rise to nematic, chiral, and topological superconductivity. As our findings are asymptotically exact for small interaction strengths, they provide a viable starting point for future studies of superconductivity in twisted transition metal dichalcogenide bilayers.