Possibility of the Kondo effect in diluted EuPd₂Si₂ systems with constant lattice volume

Specific heat C and electrical resistivity ρ between 0.2 and 300 K were investigated for Eu-diluted alloys replacing by the (La_0.67Y_0.33) component with almost constant lattice volume, on a well-known valence-transition (VT) material EuPd₂Si₂. The inter-site cooperative effect bringing the sharp VT at 150 K in EuPd₂Si₂ was revealed to be disintegrated by the dilution beyond 25 at% for Eu from the present results in both the quantities. Moreover, a logarithmic upturn in ρ below about 20 K was recognized for the samples with the dilution beyond 25 at%, correspondingly with the steep enhancement in the magnetic part of C/T reaching 500 mJ/K² Eu-mol toward the zero temperature. Discussion from the standpoint of the Kondo effect is briefly developed for the present Eu-diluted alloys.