Thermodynamics of CeNiSn at low temperatures and in weak magnetic fields

Detailed experimental and theoretical studies of the low-temperature specif ic heat, magnetic susceptibility, thermal expansion, and magnetostriction o f the orthorhombic: compound CeNiSn are presented. All anomalies observed i n the thermodynamic and magnetic properties of CeNiSn are explained in a Fr amework of a model of a metallic Kondo lattice with well developed spin-fer mion-type excitations. The pseudogap behavior of these excitations appears due to interplay between spinons and soft crystal-field states. The thermod ynamic relations for the spin liquid are derived. Together with the explana tion of inelastic neutron scattering spectra given earlier within the same approach these studies of the low-temperature thermodynamics and magnetic r esponse give a consistent description of the nature of anomalies in the low -temperature thermodynamics of perfect and imperfect CeNiSn crystals. [S016 3-1829(99)06819-8].