Pressure-induced metallization and superconductivity in the layered van der Waals semiconductor GaTe

We present a systematic high-pressure study of layered van der Waals semiconductor GaTe through electrical transport, photoluminescence, and Raman spectroscopy measurements. We report observation of pressureinduced metallization and superconductivity (SC) in GaTe simultaneously occurring at similar to 3 GPa, with an onset superconducting critical temperature of T onset C similar to 5.0 K. Analysis shows that a quasi-two-dimensional to threedimensional structural crossover plays a crucial role in driving the observed metallization and SC. Upon further C first decreases gradually and then begins to increase above similar to 10 GPa, displaying a V-shaped feature (SC-I -> SC-II) due to a structural transition (C2/m -> Fm-3m). After reaching a local maximum of 4.5 K at similar to 18 GPa, T onset C remains almost unchanged up to a highest pressure of 48.1 GPa. A comparison of the upper critical fields at different pressures spanning the SC-I and SC-II phases reveals that their pairing mechanisms may be different from each other. These results demonstrate that the band gap of layered semiconductor GaTe is highly tunable, which may stimulate further investigations by strain engineering, intercalation, and electrostatic doping.