Dilution and non-Fermi-liquid effects in the CePtIn Kondo lattice

Measurements of electrical resistivity (rho(T)), magnetoresistivity (MR), magnetic susceptibility (chi(T)) and heat capacity (C-P(T)) are presented for the (Ce1-xLax) PtIn alloy system of which the CePtIn parent is a known dense Kondo compound that does not order magnetically down to 50 mK. chi(T) for alloys 0 <= x <= 0.8 exhibits Curie-Weiss behaviour. rho(T) results indicate a transition from a dense Kondo behaviour for 0 <= x <= 0.2 to a single-ion Kondo region (0.3 <= x <= 0.8). The Kondo energy scale as given by T-K values calculated from MR studies and by the temperature T-max(rho(mag)) where the magnetic contribution to rho(T) exhibits a maximum value, is compared with theoretical models. It is shown that the experimental results not only depend on a volume effect as given by the compressible Kondo lattice model of Lavagna but in addition confirm the more complex behaviour recently presented by Burdin and Fulde for a Kondo alloy system in which the magnetic (Ce) and non- magnetic (La) atoms are distributed randomly. Non- Fermi- liquid behaviour is predicted by Burdin and Fulde at certain critical concentrations of the alloy system and experimental evidence for this is presented through chi(T), rho(T) and C-P(T) measurements.