Unique f -level resonant state within the gap in Ce3 Au3 Sb4 single crystals: Magnetic, thermal, and transport properties

The magnetic, thermal, and transport properties of single crystals of the narrow gap semiconductor Ce3 Au3 Sb4 have been studied. Transport data are consistent with an exponential activation and variable range hopping at low temperatures, which is characteristic of weak disorder and localization. The specific heat and the magnetic susceptibility data suggest the existence of a large density of states of localized states in the gap. The physics is then different from standard Kondo insulators. From its unique physical properties, we propose a three band model (valence, conduction, and f bands) with weak disorder that explains most of the experimental findings.