KONDO-LATTICE BEHAVIOR AND MULTIPLE CHARACTERISTIC TEMPERATURES IN CEIR2GE2

The results of electrical-resistivity rho measurements (1.4-300 K) on the alloys, Ce1-xLaxIr2Ge2 (0 less than or equal to x less than or equ al to 1), CeIr2-x(Rh,Pt)(x)Ge-2 (x=0.2 and 0.4), and CeIr2Ge2-x(Si,Sn) (x) (x=0.2 and 0.4), are reported in order to understand the Kondo eff ect in CeIr2Ge2. There is a significant decrease in rho as the tempera ture is lowered from 100 to 4.2 K for x=0.0. This feature disappears f or a small replacement of Ce by La (x=0.3), thereby resulting in a sin gle-ion Kondo effect for higher values of x. This finding establishes that the temperature T-coh, characterizing the coherent scattering amo ng the Kondo centers for x=0 is as large as about 100 K. The coherent scattering is not destroyed by small substitutions at the Ir or Ge sit e. The observed sensitivity of this coherence effect to a small disrup tion of Ce sublattice periodicity alone by La substitution is uncommon among trivalent Ce alloys. Such a large T-coh Value enables us to emp hasize the need to invoke three characteristic temperatures for nonmag netic Kondo lattices.