Exploring A Possible Quantum Critical Point in Ca₃(Rh_xIr_1-x)₄Sn₁₃

Single crystals of a novel stannide 3-4-13 superconductor family, Ca₃(Rh_xIr_1-x)₄Sn₁₃, were synthesized by flux growth and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), magnetization, and London penetration depth measurement techniques. Compositional variation of the Rh/Ir ratio was used to study the coexistence and competition between the charge density wave (CDW) and superconductivity. The superconducting transition temperature 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, TCDW(x). The CDW starts in pure Ir, x = 0, with TCDW ≈ 40 K and extrapolates roughly linearly to zero at x_c = 0.58 under the dome of superconductivity. We conclude that a novel Ca3(Ir1−xRhx)4Sn13 alloy with clearly competing CDW and superconductivity, is a good candidate to look for a composition-driven quantum critical point at ambient pressure.