Divalent-to-trivalent transition of Sm in SmS: Implications for the high-pressure magnetically ordered state

We present a resonant x-ray emission study of the pressure-induced valence transition of SmS. Spectra excited at the L-3 absorption edge of Sm ions were recorded at applied pressures ranging from 1 to 18 GPa, at room temperature. Thanks to its extreme sensitivity to the electronic configuration, resonant inelastic x-ray emission is well suited to follow precisely the small valence changes in the high pressure region. The Sm valence is found to increase from 2.7 at 1 GPa to 3 at 18 GPa, and the trivalent state is reached at p(c)similar to 13 GPa. Our results imply that the transition to the trivalent state at p(c) is not accompanied by any detectable change of the magnetic properties, as inferred from the nuclear forward scattering measurements, with respect to those of the intermediate valent state (p > 2 GPa).