Robust superconductivity and the suppression of charge-density wave in the quasi-skutterudites $\text{Ca}_{3}(\text{Ir}_{1-x}\text{Rh}_{x})_{4}\text{Sn}_{13}$ single crystals at ambient pressure.

The coexistence and competition between the charge density wave (CDW) and superconductivity was studied by varying the Rh/Ir ratio. The superconducting transition temperature, $T_c$, varies from 7 K in pure Ir ($x=0$)
to 8.3 K in pure Rh ($x=1$). Temperature-dependent electrical resistivity reveals monotonic suppression of the CDW transition temperature, $T_{\text{CDW}}(x)$. The CDW starts in pure Ir, $x=0$, at $T_{\text{CDW}}\approx40$~K and extrapolates roughly linearly to zero at $x_c \approx 0.53-0.58$ under the superconducting dome. Magnetization and transport measurements show a significant influence of CDW on superconducting and normal states. Meissner expulsion is substantially reduced in the CDW region, indicating competition between the CDW and superconductivity. The low-temperature resistivity is higher in the CDW part of the phase diagram, consistent with the reduced density of states due to CDW gapping. Its temperature dependence just above $T_c$ shows signs of non-Fermi liquid behavior in a cone-like composition pattern. We conclude that the $\text{Ca}_3(\text{Ir}_{1-x}\text{Rh}_x)_4\text{Sn}_{13}$ alloy is a good candidate for a composition-driven quantum critical point (QCP) at ambient pressure.
Temperature-dependent electrical resistivity reveals monotonic suppression of the CDW transition temperature, $T_{\text{CDW}}(x)$. The CDW starts in pure Ir, $x=0$, at $T_{\text{CDW}}\approx40$~K and extrapolates roughly linearly to zero at $x_c \approx 0.53-0.58$ under the superconducting dome. Magnetization and transport measurements show a significant influence of CDW on superconducting and normal states. Meissner expulsion is substantially reduced in the CDW region, indicating the competition between the CDW and superconductivity. The low-temperature resistivity is higher in the CDW part of the phase diagram, consistent with the reduced density of states due to CDW gapping. Its temperature dependence just above $T_c$ shows clear signs of non-Fermi-liquid behavior in a cone-like composition pattern. We conclude that the $\text{Ca}_3(\text{Ir}_{1-x}\text{Rh}_x)_4\text{Sn}_{13}$ alloy is a good candidate for a composition-driven quantum critical point (QCP) at ambient pressure.