Reduced moment magnetic ordering in a Kondo lattice compound: Ce8Pd24Ga

The magnetic ground state of the antiferromagnet Kondo lattice compound ${\mathrm{Ce}}_{8}{\mathrm{Pd}}_{24}\mathrm{Ga}$ has been investigated using neutron powder diffraction, inelastic neutron scattering and zero-field muon spin relaxation measurements. The neutron diffraction analysis, below ${T}_{N}$ $(3.6\ifmmode\pm\else\textpm\fi{}0.2\mathrm{K}),$ reveals a commensurate type-C antiferromagnetic structure with the ordered state magnetic moment of $\ensuremath{\sim}0.36{\ensuremath{\mu}}_{B}/\mathrm{Ce}$-atom along the cubic 〈111〉 directions. The analysis of the inelastic neutron scattering data based on the crystal field (CF) model reveals a doublet ground state with a ground state moment of $1.29{\ensuremath{\mu}}_{B}/\mathrm{Ce}$-atom. The observed magnetic moment from neutron diffraction, which is small compared to the expected value from CF analysis, is attributed to screening of the local Ce moment by the Kondo effect. This is supported by the observed Kondo-type resistivity and a small change in the entropy of ${\mathrm{Ce}}_{8}{\mathrm{Pd}}_{24}\mathrm{Ga}$ at ${T}_{N}.$ The zero-field muon spin relaxation rate exhibits a sharp increase below ${T}_{N}$ indicating ordering of Ce moments, in agreement with the neutron diffraction data. The present studies reveal that the physical properties of ${\mathrm{Ce}}_{8}{\mathrm{Pd}}_{24}\mathrm{Ga}$ are governed by the on-site Kondo compensation, the moment stabilizing intersite RKKY interaction and the crystal field effect.