Insulator-to-superconductor transition in quasi-one-dimensional HfS3 under pressure

TL;DR

This study demonstrates that highly insulating HfS3 can undergo an insulator-to-superconductor transition under high pressure, revealing potential superconductivity in non-metal TMTC compounds and expanding understanding of their electronic phases.

Contribution

It is the first to show pressure-induced superconductivity in an insulating TMTC, specifically HfS3, highlighting a new pathway for discovering superconductivity in similar materials.

Findings

HfS3 transitions from insulator to superconductor under high pressure.

Superconductivity in HfS3 appears above 50.6 GPa, with zero resistance above 91.2 GPa.

Structural changes accompany the electronic transition, confirmed by optical and Raman measurements.

Abstract

Various transition metal trichalcogenides (TMTC) show the charge-density-wave and superconductivity, which provide an ideal platform to study the correlation between these two orderings and the mechanism of superconductivity. 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 the superconductivity exist in any non-metal TMTC compound? In this work, we managed to manipulate the electronic behavior of highly insulating HfS3 in term of pressure. HfS3 underwent an insulator-semiconductor transition near 17 GPa with a band gap reduce of ~1 eV. The optical absorption and Raman measurement provide the consistent results, suggesting the structural origin of the electronic transition. Upon further compression, HfS3 becomes a superconductor. The superconducting transition was initialized as early as 50.6 GPa and the zero-resistance is reached above 91.2 GPa. The superconducting behavior is further confirmed by both the magnetic field effect and current effect. This work sheds the light that all TMTC may be superconductors, and opens a new avenue to explore the abundant emergence phenomena in TMTC material family.