Lu and La substituted Ce3Pd20Si6

Abstract

In order to disentangle the effects of the two different crystallographic Ce sites in Ce3Pd20Si6 on the intriguing lowtemperature properties of this compound, we have investigated polycrystalline samples of Ce3-xLuxPd20Si6 (x = 1,2) and Ce3-yLayPd20Si6 (y = 1,2). The lattice parameters and electrical resistivity measurements in the temperature range 2-300K are presented. Lu-substitution leads to a considerable decrease in the unit cell volume, corresponding to positive chemical pressure, while substitution with La expands the lattice much more gradually.We interpret the observed shifts in the characteristic temperatures for the onset of incoherent and coherent Kondo scattering, Tmin and Tmax, respectively, by competing effects of chemical pressure and density of Kondo scatterers. We also investigate the important issue of preferential site occupation by Lu and La and present evidence for Ce2LaPd20Si6 being an essentially ordered compound. The incoherent Kondo scattering dominating the electrical resistivity of Ce3Pd20Si6 between 20 and 300K appears to be caused by Ce at the 8c-site only. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.