Crystal field manifestation in inelastic neutron scattering, magnetic susceptibility and specific heat of the antiferromagnetic CeCoAl4

Inelastic and quasielastic excitations in the neutron scattering on the compounds CeCo1−xCuxAl4CeCo1−xCuxAl4 (x  =0, 0.05, 0.1) have been studied above and below the antiferromagnetic ordering temperature. The quasielastic contribution disappears below the Néel temperature, TN=13.5K, and its linewidth Γ/2Γ/2 is below TNTN, therefore these results suggest that Kondo screening is not relevant in these Ce compounds. Based on the example of CeCoAl4 we show that the inelastic excitations provide crystal electric field energy levels scheme, which in consistent way describes both the magnetic susceptibility and the specific heat. The inelastic neutron scattering spectrum below TNTN is interpreted as the splitting of the crystal electric field levels by the internal molecular field.

•Kondo screening is not relevant in CeCoAl4.•Consistent CEF levels scheme from complementary methods.•Splitting of the CEF levels below the Néel temperature.•Mixing of states in the ground state.