High pressures and the Kondo gap in Ce3Bi4Pt3

Abstract

We have measured the electrical resistivity p(T) of single crystals of Ce-3Bi4Pt3 for temperatures from 1.2 to 300 K, and pressures from I bar to 145 kbar. The transport is dominated at high temperatures by excitations across a small activation gap a, which increases rapidly with pressure. The low-temperature transport involves variable range hopping among extrinsic states in the gap. The spatial extent of the in-gap states reflects coupling to conduction-electron states, and is strongly modified as pressure enhances Delta. Despite the strong pressure dependence of Delta, a direct correspondence between single-ion energetics and the measured gap is maintained, and the role of valence fluctuations is minimal even at the highest pressures.