Superconducting Dome in a Gate-Tuned Band Insulator

TLDR

A dome-shaped superconducting region appears in the phase diagrams of many unconventional superconductors, but such optimal superconductivity is rarely seen in doped band insulators. We report the observation of a superconducting dome in the temperature–carrier density phase diagram of MoS₂, an archetypal band insulator. Quasi‑continuous electrostatic carrier doping was achieved by combining liquid and solid gating, enabling exploration of the low‑carrier density regime. The resulting large enhancement of T_c at optimal doping demonstrates that a superconducting dome can arise in doped band insulators.

Abstract

A dome-shaped superconducting region appears in the phase diagrams of many unconventional superconductors. In doped band insulators, however, reaching optimal superconductivity by the fine-tuning of carriers has seldom been seen. We report the observation of a superconducting dome in the temperature-carrier density phase diagram of MoS(2), an archetypal band insulator. By quasi-continuous electrostatic carrier doping achieved through a combination of liquid and solid gating, we revealed a large enhancement in the transition temperature T(c) occurring at optimal doping in the chemically inaccessible low-carrier density regime. This observation indicates that the superconducting dome may arise even in doped band insulators.