On the interplay between heavy-fermion and soft crystal field excitations in Kondo lattices

On the grounds of the microscopic theory of heavy-fermion spin-liquids a novel description of low-energy excitation spectra in CeNiSn and related compounds is offered. The anomalous properties of orthorhombic CeNiSn and related materials are explained by the interplay between the fermi-type spinon excitations with the energy scale T* ≈ T_K and the one-site crystal field excitations with the energy Δ_CF < T*. The theory gives quantitative description of inelastic neutron scattering spectra. It resolves also the apparent contradiction between metallic conductivity and gap-wise behavior of thermodynamic properties and spin response at low temperatures.