Electronic structure of black SmS. II. Angle-resolved photoemission spectroscopy

Abstract

We have studied the electronic band structure of semiconducting black SmS with high-resolution angle-resolved photoemission spectroscopy (ARPES). The valence band consists of two well-separated groups of bands: almost nondispersive bands near E F and highly dispersive bands at higher binding energy. The former is ascribed to the Sm 2 (4f 6 →4f 5 ) multiplet and the latter to mainly the S 3p states. We found a small but distinct energy dispersion in the Sm 4f-derived bands near E F . This indicates a strong hybridization between the localized Sm 4f electrons and the itinerant conduction electrons, leading to the delocalized Sm 4f states in mixed-valent SmS. We have compared the present ARPES results with a recent periodic Anderson model calculation [C. Lehner et al., Phys. Rev. B 58, 6807 (1998)].