The $\mathrm{Ce}{\mathrm{Pd}}_{1-x}{\mathrm{Rh}}_x$ alloy exhibits a continuous evolution from ferromagnetism $(T_C=6.5\mathrm{K})$ at $x=0$ to a mixed-valence (MV) state at $x=1$. We have performed a detailed investigation on the suppression of the ferromagnetic (F) phase in this alloy using dc $\left({\chi }_{\mathrm{dc}}\right)$ and ac $\left({\chi }_{\mathrm{ac}}\right)$ susceptibility, specific heat $\left(C_m\right)$, resistivity $\left(\rho \right)$, and thermal expansion $\left(\beta \right)$ techniques. Our results show a continuous decrease of $T_C\left(x\right)$ with negative curvature down to $T_C=3\mathrm{K}$ at $x^{*}=0.65$, where a positive curvature takes over. Beyond $x^{*}$, a cusp in ${\chi }_{\mathrm{ac}}$ is traced down to $T_C^{*}=25\mathrm{mK}$ at $x=0.87$, locating the critical concentration between $x=0.87$ and 0.90. The quantum criticality of this region is recognized by the $-\log (T∕T_0)$ dependence of $C_m∕T$, which transforms into a $T^{-q}$ $(q\approx 0.5)$ one at $x=0.87$. At high temperature, this system shows the onset of valence instability revealed by a deviation from Vegard’s law (at $x_V\approx 0.75$) and increasing hybridization effects on high-temperature ${\chi }_{\mathrm{dc}}$ and $\rho \left(T\right)$. Coincidentally, a Fermi liquid contribution to the specific heat $\left(\gamma \right)$ arises from the MV component, which becomes dominant at the CeRh limit. In contrast to antiferromagnetic systems, no $C_m∕T$ flattening is observed for $x>x_{\mathit{cr}}$ but, rather, the mentioned power-law divergence, which coincides with a change of sign of $\beta \left(T\right)$. The coexistence of F and MV components and the sudden changes in the $T$ dependencies are discussed in the context of randomly distributed magnetic and Kondo couplings.

• Received 31 August 2006

DOI:https://doi.org/10.1103/PhysRevB.75.024432