Bandwidth-tuned Mott transition and superconductivity in moiré WSe₂.

Abstract

The emergence of high-transition-temperature (T_c) superconductivity in strongly correlated materials remains the main unsolved problem in physics. High-T_c materials, such as cuprates, are generally complex and not easily tunable, making theoretical modelling difficult. Although the Hubbard model-a simple theoretical model of interacting electrons on a lattice-is believed to capture the essential physics of high-T_c materials^1-5, obtaining accurate solutions of the model, especially in the relevant regime of moderate correlation, is challenging⁶. The recent demonstration of robust superconductivity in moiré WSe₂ (refs. ^7,8), in which low-energy electronic bands can be described by the Hubbard model and are highly tunable^9-11, presents a new platform for studying the high-T_c problem. Here we tune moiré WSe₂ bilayers to the moderate correlation regime through the twist angle and map the phase diagram around one hole per moiré unit cell (ν = 1) by electrostatic gating and electrical transport and magneto-optical measurements. We observe a range of high-T_c phenomenology, including an antiferromagnetic insulator at ν = 1, superconducting domes on electron and hole doping, and unusual metallic states such as strange metals^12-14. Twist-angle dependence studies further show that the highest T_c always occurs adjacent to the Mott transition^3,15. Our results indicate strong correlation as the key to superconductivity in moiré WSe₂ and establish a new material system for studying high-T_c superconductivity in a controllable manner.