Ce 4f-LIGAND DEHYBRIDIZATION IN CeT2X2-BASED KONDO LATTICE/HEAVY FERMION SYSTEMS

Abstract

The lattice parameters of two CeT2X2 ( T =3d transition elements and X=Si and Ge) based Kondo lattice systems, the CeNi2-xCux Si2 and Ce(NiSi)2-x (CuGe)x, have been studied. The analysis of the Ce-ligand distances indicates that the variation of the a-parameter dominantly affects Ce 4f-X ligandn orbital hybridization whereas the variation of c-parameter dominantly affects Ce 4f-T ligand orbital hybridization. The average Ce-ligand distance varies linearly with x across the whole series in spite of the abnormal increase of the c-parameter in the region 1.6 ≤ x ≤ 2.0. Thus, our analysis shows that the average Ce 4f-ligand orbital hybridization decreases uniformly with x across the entire range of x for the CeNi2-xCuxSi 2 and Ce(NiSi)2-x(CuGe)x series. The means that the Ce 4f-ligand orbital dehybridization may not be a key factor to the formation of the heavy-fermion ground state in CeCu2Si2.