Pressure-Induced Dome-Like Superconductivity and Unusual Charge-Density-Wave-Like Transition in Th₂Cu₄As₅

The recently discovered Cu₄As₃-type material Th₂Cu₄As₅ has been reported to exhibit both superconductivity and charge density wave (CDW) orders. These two electronic phenomena might originate from distinct structural units in Th₂Cu₄As₅, providing a unique platform to investigate the interplay between superconductivity and CDW. In this work, we carried out high-pressure electrical transport and X-ray diffraction measurements to track the evolution of the CDW and superconductivity at high pressure. Superconductivity can initially be enhanced upon the suppression of the CDW transition and then gradually decrease with increasing pressure after the CDW transition is completely suppressed, displaying a characteristic dome-like behavior. More intriguingly, a 2 × 2 × 5 superlattice appears at pressures exceeding 8 GPa, which coincides with the sudden loss of superconductivity. This observation indicates the presence of an unusual possible CDW state that may be linked to the Cu₄As₃ superconducting layer. Our results unveil versatile CDW states in pressurized Th₂Cu₄As₅, which provide us with a rare platform to investigate the interplay of multiple electronic ordered states.