Hydrothermal synthesis and complete phase diagram of FeSe1−xSx (0≤x≤1) single crystals

We report the successful synthesis of FeSe1-xSx single crystals with x ranging from 0 to 1 via a hydrothermal method. A complete phase diagram of FeSe1-xSx has been obtained based on resistivity and magnetization measurements. The nematicity is suppressed with increasing x, and a small superconducting dome appears within the nematic phase. Outside the nematic phase, the superconductivity is continuously suppressed and reaches a minimum T-c at x = 0.45; beyond this point, T-c slowly increases until x = 1. Intriguingly, an anomalous resistivity upturn with a characteristic temperature T* in the intermediate region of 0.31 <= x <= 0.71 is observed. T* shows a domelike behavior with a maximum value at x = 0.45, which is opposite the evolution of T-c, indicating competition between T* and superconductivity. The origin of T* is discussed in detail. Furthermore, the normal state resistivity evolves from non-Fermi-liquid to Fermi-liquid behavior with S doping at low temperatures, accompanied by a reduction in electronic correlations. Our study addresses the lack of single crystals in the high-S doping region and provides a complete phase diagram, which will promote the study of relations among nematicity, superconductivity, and magnetism.