Abstract
Inelastic neutron scattering experiments have been carried out to determine the crystal-field states of the Kondo lattice heavy fermions and . Both the compounds crystallize in -type cubic structure (space group ) in which the Ce atoms occupy two distinct crystallographic sites with cubic and tetragonal point symmetries. The INS data of reveal the presence of a broad excitation centered around 6–8 meV, which is accounted by a model based on crystal electric field (CEF) excitations. On the other hand, the INS data of isostructural reveal three CEF excitations around 7.0, 12.2, and 37.2 meV. The neutron intensity sum rule indicates that the Ce ions at both cubic and tetragonal Ce sites are in state in both and . The CEF level schemes for both the compounds are deduced. We estimate the Kondo temperature K for from neutron quasielastic linewidth in excellent agreement with that determined from the scaling of magnetoresistance which gives K. For , the neutron quasielastic linewidth gives K. For both and , the ground state of turns out to be a quartet for the cubic site and a doublet for the tetragonal site.
6 More- Received 3 February 2016
- Revised 28 June 2016
DOI:https://doi.org/10.1103/PhysRevB.94.014440
©2016 American Physical Society