Cd doping effects in the heavy-fermion compounds Ce2 MIn 8 ( M=Rh and Ir)

摘要: Low-temperature magnetic properties of Cd-doped ${\text{Ce}}_{2}M{\text{In}}_{8}$ ($M=\text{Rh}$ and Ir) single crystals are investigated. Experiments temperature-dependent magnetic-susceptibility, heat-capacity, electrical-resistivity measurements revealed that Cd doping enhances the antiferromagnetic (AFM) ordering temperature from ${T}_{N}=2.8\text{ }\text{K}$ $(x=0)$ to ${T}_{N}=4.8\text{ $(x=0.21)$ for ${\text{Ce}}_{2}{\text{RhIn}}_{8\ensuremath{-}x}{\text{Cd}}_{x}$ induces long-range AFM with ${T}_{N}=3.8\text{ ${\text{Ce}}_{2}{\text{IrIn}}_{8\ensuremath{-}x}{\text{Cd}}_{x}$. Additionally, x-ray neutron scattering studies showed samples present below ${T}_{N}$ a commensurate structure propagation vector $\stackrel{P\vec}{\ensuremath{\epsilon}}=(\frac{1}{2},\frac{1}{2},0)$. The resolved structures both compounds indicate tends rotate direction ordered moments toward $ab$ plane. This result suggests affects ${\text{Ce}}^{3+}$ ground-state single-ion anisotropy modifying crystalline electrical field (CEF) parameters at site. Indications CEF evolution induced by were also found in measurements. Comparisons between our results general effects on related $\text{Ce}M{\text{In}}_{5}$ ($M=\text{Co}$, Rh, confirms claims electronic tuning is main effect favoring these compounds.