Structural and electronic transitions in the low-temperature, high-pressure phase of SmS

Structural and electronic properties of samarium sulfide were studied under pressure up to 2.9 GPa and at low temperatures down to 4.5 K via x-ray diffraction and absorption techniques. The measurements are a direct probe of the valence and structural state of samarium sulphide at low temperatures through the black-to-gold and magnetic transitions. A divalent state is found below the first-order valence transition reached in this study at 58 K and 1.13 GPa. Above the transition, the valence increases linearly with pressure. In particular, it is found the samarium has an intermediate valence [2.81 (4)] in the magnetically ordered phase at 2.9 GPa and 4.5 K. Resonant x-ray magnetic scattering found no evidence of type I or type IA magnetic order in the magnetically orderded phase.