Chemical pressure effects on the Kondo behaviour of CePt<SUB>2</SUB>Ge<SUB>2</SUB>

The compound, CePt2Ge2, recently reported to crystallize in a monoclinic modification of the CaBe2Ge2 structure, has been identified to be an antiferromagnetic Kondo lattice (TN=2.2 K). The influence of positive and negative chemical pressure on the Kondo behavior is investigated by measurements of magnetic susceptibility and electrical resistivity (ρ) on the solid solutions, Ce1-x Lax Pt2Ge2 and Ce1-z Yz Pt2Ge2. Y and La substituents cause nearly similar effects on the magnetic and electrical resistivity behaviour of CePt2Ge2, though the unit-cell volumes vary in opposite directions. We propose that the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction may contribute to decide the temperature at which ρ attains a maximum at low temperatures (~5 K) in CePt2Ge2