The microscopic theory of interaction between the heavy fermions and the crystal field excitations in Kondo lattices is presented. It is shown that the heavy-fermion spectrum scaled by the Kondo temperature $T_K$ can be modified by the crystal field excitations with the energy $\Delta_{ CF}$ provided the inequality $\Delta_{ CF}<T_K$ is realized. On the base of general description of excitation spectrum the detailed qualitative and quantitative explanation of anisotropic inelastic neutron scattering spectra and low-temperature specific heat of orthorhombic CeNiSn is given. The theory resolves the apparent contradiction between the metallic conductivity and the gap-wise behavior of thermodynamic properties and spin response of CeNiSn at low temperatures.
Categories: cond-mat.str-el