Crystal field in the CeAl3 heavy-fermion compound

Abstract

An analysis of inelastic neutron scattering in the CeAl3 heavy fermion compound is presented. Using single-crystal magnetic-susceptibility and inelastic neutron scattering data, an unambiguous solution for the set of parameters of the electric crystal field Hamiltonian is obtained: B20 = (5.8 ± 0.2) × 10−2 meV and B40 = (2.3 ± 0.1) × 10−2 meV. The energy level scheme for the ground-state multiplet of the Ce3+ ion in CeAl3 consists of the ground level Γ9❘±3/2〉 and two doublets Γ8❘±5/2〉 and Γ7❘±1/2〉 having close energies of ∼6.3 meV at a temperature of 20 K. As follows from comparing the crystal-field parameters in the RAl3 series (R = Ce, Pr, Nd), the fact that the parameters A20〈r2〉 and A40〈r4〉 in CeAl3 differ significantly in value from the respective parameters in PrAl3 and NdAl3 cannot be explained in terms of the lattice constants of these isostructural compounds being different but rather is due to the enhanced hybridization of the localized 4f electrons of cerium with conduction electrons.