Thermodynamics of cenisn at low temperatures and in weak magnetic fields

Detailed experimental and theoretical studies of the low-temperature specific heat, magnetic susceptibility, thermal expansion, and magnetostriction of the orthorhombic compound CeNiSn are presented. All anomalies observed in the thermodynamic and magnetic properties of CeNiSn are explained in a framework of a model of a metallic Kondo lattice with well developed spin-fermion-type excitations. The pseudogap behavior of these excitations appears due to interplay between spinons and soft crystal-field states. The thermodynamic relations for the spin liquid are derived. Together with the explanation of inelastic neutron scattering spectra given earlier within the same approach these studies of the low-temperature thermodynamics and magnetic response give a consistent description of the nature of anomalies in the low-temperature thermodynamics of perfect and imperfect CeNiSn crystals.