Abstract
The evolution of the behavior of the Ce electron with the Cu content in the alloy Ce was investigated by determining its structural, magnetic, transport, and thermal properties. Results obtained on 15 samples with compositions distributed along the whole concentration range allow us to draw a magnetic phase diagram showing three distinct regions. The first region at low Cu concentrations corresponds to the antiferromagnetic-ordered regime. The fast suppression of this magnetic order between and suggests the presence of a critical point which separates this region from the second one at larger values where no magnetic order is observed. The main characteristic of this second region, which extends up to , is a pronounced increase of the Kondo temperature from K at to K at . This is in contrast with the fast decrease of in the region with . In this region a small anomaly with a ferromagnetic character is observed in the specific heat arround 4 K. The change in the evolution of with coincides with a change in the composition dependence of the lattice parameter of the tetragonal structure, pointing to a structure-related origin of this unusual behavior. This nonmonotonous dependence is reproduced using local-density-approximation band-structure calculations, which show a maximum of the hybridization strength between conduction electrons and Ce states for intermediate Cu concentrations. Such a dependence which contradicts the monotonous dependence observed in all other Ce-based alloy systems is the hallmark of the Ce alloy, which cannot be described as a Fermi-liquid system in the nonmagnetic region.
- Received 29 August 1997
DOI:https://doi.org/10.1103/PhysRevB.58.314
©1998 American Physical Society