Single crystals of $\mathrm{Ce}{\mathrm{Rh}}_{1-x}{\mathrm{Co}}_x{\mathrm{In}}_5$ have been investigated by means of specific heat measurements at zero pressure and electrical resistivity measurements under nearly hydrostatic pressure up to $28\mathrm{kbar}$. Specific heat measurements for samples of $\mathrm{Ce}{\mathrm{Rh}}_{1-x}{\mathrm{Co}}_x{\mathrm{In}}_5$ with cobalt concentrations of $x=0.65$, 0.71, 0.77, 0.87, and 0.93 confirm the existence of antiferromagnetism for $0⩽x⩽0.7$ and suggest the existence of a quantum critical point at $x_c\sim 0.75$. Entropy versus $x$ isotherms below $\sim 5\mathrm{K}$ and the normalized residual resistivity $\rho \left(0\mathrm{K}\right)∕\rho \left(290\mathrm{K}\right)$ versus $x$ curve both display maxima near $x_c\sim 0.75$, suggesting further evidence for the existence and location of the quantum critical point. Electrical resistivity measurements under pressure for samples with $x=0.1$, 0.2, 0.4, and 0.6 reveal antiferromagnetism, pressure-induced superconductivity, and the coexistence of antiferromagnetism and superconductivity. Normalized residual resistivity $\rho \left(0\mathrm{K}\right)∕\rho \left(290\mathrm{K}\right)$ versus pressure $P$ curves and the evolution of the power-law exponent $n$ favor the existence of quantum critical points at critical pressures $P_c\sim 23\mathrm{kbar}$, $\sim 21\mathrm{kbar}$, and $\sim 7\mathrm{kbar}$ for samples with $x=0.1$, 0.2, and 0.4, respectively.

• Received 25 January 2005

DOI:https://doi.org/10.1103/PhysRevB.72.024551