Unusual Kondo-hole effect and crystal-field frustration in Nd-doped CeRhIn$_{5}$

We investigate single crystalline samples of Ce$_{1-x}$Nd$_{x}$RhIn$_{5}$ by means of X-ray diffraction, microprobe, magnetic susceptibility, heat capacity, and electrical resistivity measurements. Our data reveal that the antiferromagnetic transition temperature of CeRhIn$_{5}$, $T_{N}^{\mathrm{Ce}} = 3.8$ K, is linearly suppressed with $x_{\mathrm{Nd}}$, by virtue of the "Kondo hole" created by Nd substitution. The extrapolation of $T^{\mathrm{Ce}}_{N}$ to zero temperature, however, occurs at $x_{c} \sim 0.3$, which is below the 2D percolation limit found in Ce$_{1-x}$La$_{x}$RhIn$_{5}$. This result strongly suggests the presence of crystal-field frustration effects. Near $x_{\mathrm{Nd}} \sim 0.2$, the Ising AFM order from Nd ions is stabilized and $T^{\mathrm{Nd}}_{N}$ increases up to $11$ K in pure NdRhIn$_{5}$. Our results shed light on the effects of magnetic doping in heavy-fermion antiferromagnets and stimulate the study of such systems under applied pressure.