Superconductivity in Metal Sulfides.

The exploration of high-temperature superconductors and the mechanisms underlying continues to present significant challenges in condensed matter physics. Identifying new potential superconducting platforms is critical for advancing our understanding of superconductivity and its interactions with other quantum states. Metal sulfides constitute a diverse family of materials that exhibit unique physical properties, with crystal structures that can be tailored from one-dimensional (1D) to three-dimensional (3D) by varying the metal-to-sulfur ratio. Recent investigations into the superconductivity of metal sulfides have revealed extraordinary quantum phenomena, including chiral superconductivity, two-dimensional Ising superconductivity, and the competition between charge density waves (CDW) and superconductivity. Furthermore, pressure tuning-a refined technique for modifying electronic and crystal structures without introducing impurities-has facilitated the emergence of superconductivity in various semiconducting and even insulating metal sulfides. In this review, we summarize and analyze the rich superconducting properties of metal sulfides, encompassing 3D metal monosulfides, 2D metal disulfides, and quasi-1D transition metal trisulfides. We also discuss additional systems, including hydrogen sulfides, Th₃P₄-type sulfides, and Bi-S systems. Collectively, these findings underscore that metal sulfides not only represent promising superconducting materials but also serve as excellent platforms for further investigation into the mechanisms of superconductivity.