Insulator-to-Superconductor Transition in Quasi-One-Dimensional HfS3 under Pressure

Various transition-metal trichalcogenides (TMTC) show unique electronic properties, such as metal-insulator transition, topological insulator, and even superconducting transition. Currently, almost all metallic TMTC compounds can show superconductivity either at ambient pressure or at high pressure. However, most TMTC compounds are semiconductors and even insulators. Does superconductivity exist in any non-metallic TMTC compound by artificial manipulation? In this work, the electronic behavior of highly insulating HfS3 has been manipulated in terms of pressure. HfS3 undergoes an insulator-to-semiconductor transition near 17 GPa with a band gap reduction of -1 eV. Optical absorption, Raman spectroscopy, and X-ray diffraction measurements provide consistent results, suggesting the structural origin of the electronic transition. Upon further compression, HfS3 becomes a superconductor without further structural transition. The superconducting transition occurs as early as 50.6 GPa, and the Tc reaches 8.1 K at 121 GPa, which sets a new record for TMTCs. This work reveals that all TMTCs may be superconductors and opens a new avenue to explore the abundant emergent phenomena in the TMTC material family.

Automated summary

In this study, the high insulating behavior of HfS3 was manipulated through pressure. It was found that HfS3 undergoes an insulator-to-semiconductor transition near 17 GPa, with a reduction in band gap of -1 eV. Optical absorption, Raman spectroscopy, and X-ray diffraction measurements provided consistent results, indicating the structural origin of the electronic transition. Additionally, HfS3 exhibited superconductivity at high pressure, with a record Tc of 8.1 K at 121 GPa. This work suggests that all TMTCs may have the potential to be superconductors and opens up new possibilities for exploring emergent phenomena in the TMTC material family.