Anomalous metal-semiconductor transition and superconductivity in van der Waals TiS2 under pressure

Abstract

Van der Waals transition-metal dichalcogenides (TMDCs) form a vast family that has garnered significant attention in various fields. Among these, TiS2 has complex and controversial electronic properties at ambient and high pressures that need clarification, such as its semiconductor/metal nature, ambiguous high pressure structures, disputed electronic behaviors under pressure, etc. In this work, we confirm the anomalous metal-semiconductor-metal transition and reveal the emergence of superconductivity in TiS2. This metal-semiconductor transition near 15 GPa is clarified as an intrinsic property of single-crystal TiS2 due to the self-Ti-doping and an isostructural transition. Re-metallization occurs at 31 GPa, and superconductivity emerges above 88 GPa. The critical temperature Tc increases monotonically with pressure, reaching 4.1 K at 136.6 GPa, and is still not saturated. As the lightest TMDC and the first superconducting layered fourth-period transition-metal disulfide, TiS2 offers valuable insights into its unique electronic properties. This research not only reveals the anomalous metal-semiconductor transition and superconductivity but also inspires further investigation into the evolution of electronic properties in other TMDCs under pressure.

Source-reported materials — not catalogue approval

Similar papers