Twist angle evolution of phase diagram in bilayer WSe2

Recent experiments have found superconductivity in twisted bilayer WSe2 (tWSe2), extending the family of two-dimensional flat-band superconductors beyond twisted and rhombohedral graphene systems. An important feature of twisted transition metal dichalcogenides (TMDs) is that correlated electronic phases appear across a broad, continuous range of twist angles. In tWSe2, distinct superconducting phase diagrams were observed at two different twist angles, 3.65° and 5.0°, one in proximity to an insulating state and one in proximity to a metallic fermi surface reconstructed phase, raising the questions of whether the two superconductors share a similar origin. Here we address the question by mapping the evolution of the phase diagram with twist angle between 3.8° and 5.0°. As the twist angle decreases, both superconductivity (SC) and its adjacent antiferromagnetic (AFM) ordering shift towards lower displacement field and density. The AFM onset temperature increases while the superconducting critical temperature decreases. At sufficiently low twist angle, the AFM region overlaps half filling moiré density and insulating gaps emerge. The superconducting state becomes marginal or manifests as a "failed superconductor", a mixed phase of SC and resistive states. Our results connect the previously distinct phase diagrams at 3.65° and 5°, and offer new insight into the origin of the superconductors in this system.