Superconducting dome by tuning through a van Hove singularity in a two-dimensional metal

Abstract Chemical substitution is a promising route for the exploration of rich variety doping- and/or disorder-dependent collective phenomena in low-dimensional quantum materials. Here we show that transition metal dichalcogenide alloys are ideal platforms to this purpose. In particular, demonstrate emergence superconductivity otherwise metallic single-layer TaSe 2 by minute electron doping provided substitutional W atoms. We investigate temperature and magnetic field dependence superconducting state Ta 1-δ δ Se with ( ) using variable (0.34–4.2 K) scanning tunneling spectroscopy (STS). unveil dome spanning 0.003 < 0.03 maximized critical 0.9 K, significant increase from bulk T C = 0.14 K). Superconductivity emerges an density states (DOS) as Fermi surface approaches van Hove singularity due doping. Once reached, however, DOS decreases , which gradually weakens state, thus shaping dome. Lastly, our doping-dependent measurements suggest development Coulomb glass phase triggered disorder dopants.