Structural and electrical properties of epitaxial perovskite CaIr_1-xRu_xO₃ thin films

The 4d and 5d transition metal oxides have exhibited a wide spectrum of attracting phenomena. Here, we demonstrate modulations on crystal structure, electrical properties, and spin-orbit couplings (SOCs) in perovskite CaIr_1-xRu_xO₃ (CIRO, 0 ≤ x ≤ 1) thin films. First, all our coherently-grown CIRO films exhibit the orthorhombic perovskite structure, of which the orthorhombicity is tuned by the doping level x. This is different from the post-perovskite structure that is usually observed in the bulk CaIrO₃. Second, the metal-semiconductor transition in the perovskite CIRO layers is triggered by changing either the doping level or the layer thickness. Our data suggest the important roles of SOC and disorders in determining the electrical properties in perovskite CIRO layers. Third, the sign reversal of Hall coefficient in CIRO films reveals the complex evolution of electronic structure depending on x and temperature, suggesting the perovskite CIRO films as a new accessible platform for investigating rich physics in 4d and 5d transition metal oxides.