Metallization of Quantum Material GaTa4Se8 at High Pressure

Pressure is a unique thermodynamic variable to explore the phase competitions and novel phases inaccessible at ambient conditions. The resistive switching material GaTa4Se8 displays several quantum phases under pressure, such as a J eff = 3/2 Mott insulator, a correlated quantum magnetic metal, and d-wave topological superconductivity, which has recently drawn considerable interest. Using high-pressure Raman spectroscopy, X-ray diffraction, extended X-ray absorption, transport measurements, and theoretical calculations, we reveal a complex phase diagram for GaTa4Se8 at pressures exceeding 50 GPa. In this previously unattained pressure regime, GaTa4Se8 ranges from a Mott insulator to a metallic phase and exhibits superconducting phases. In contrast to previous studies, we unveil a hidden correlation between the structural distortion and band gap prior to the insulator-to-metal transition, and the metallic phase shows superconductivity with structural and magnetic properties that are distinctive from the lower-pressure phase. These discoveries highlight that GaTa4Se8 is a unique material to probe novel quantum phases from a structural, metallicity, magnetism, and superconductivity perspective.