Coupled ferroelectricity and superconductivity in bilayer Td-MoTe2

Achieving electrostatic control of quantum phases is at the frontier of condensed matter research. Recent investigations have revealed superconductivity tunable by electrostatic doping in twisted graphene heterostructures and in two-dimensional semimetals such as WTe₂ (refs. ^1–5). Some of these systems have a polar crystal structure that gives rise to ferroelectricity, in which the interlayer polarization exhibits bistability driven by external electric fields^6–8. Here we show that bilayer T_d-MoTe₂ simultaneously exhibits ferroelectric switching and superconductivity. Notably, a field-driven, first-order superconductor-to-normal transition is observed at its ferroelectric transition. Bilayer T_d-MoTe₂ also has a maximum in its superconducting transition temperature (T_c) as a function of carrier density and temperature, allowing independent control of the superconducting state as a function of both doping and polarization. We find that the maximum T_c is concomitant with compensated electron and hole carrier densities and vanishes when one of the Fermi pockets disappears with doping. We argue that this unusual polarization-sensitive two-dimensional superconductor is driven by an interband pairing interaction associated with nearly nested electron and hole Fermi pockets.