Non-Fermi-liquid behavior in single-crystal CaRuO₃: Comparison to ferromagnetic SrRuO₃

We report calorimetric, magnetic and electric transport properties of single-crystal CaRuO₃ and SrRuO₃ as a function of temperature T and applied magnetic field B. We find that CaRuO₃ is a non-Fermi-liquid metal near a magnetic instability, as characterized by the following properties: (1) the heat capacity C (T, B) ∼ - T log T is readily enhanced in low applied fields, and exhibits a Schottky peak at 2.3 K that exhibits field dependence when T is reduced; (2) the magnetic susceptibility diverges as T^{- γ} at low temperatures with 1 / 2 < γ < 1, depending on the applied field; and (3) the electrical resistivity exhibits a T^{3 / 2} dependence over the range 1.7 < T < 24 K. No Shubnikov-de Haas oscillations are discerned at T = 0.65 K for applied fields up to 45 T. These properties, which sharply contrast those of the itinerant ferromagnet SrRuO₃, indicate CaRuO₃ is a rare example of a stoichiometric oxide compound that exhibits non-Fermi-liquid behavior near a quantum critical point.