Electronic Transport in CaIrO₃ Epitaxial Thin Films

Within the complex oxide family, there has been recent interest in the study of materials that have strong spin-orbit coupling and electron-electron interactions as they hold potential for realizing topological states and other novel emergent phenomena. In the bulk, perovskite CaIrO₃ is a semimetal with strong spin-orbit coupling that is reported to have electron mobility values up to 60,000 cm²/Vs and predicted to host Dirac electrons. The coexistence of high carrier mobility and strong spin-orbit coupling in CaIrO₃ makes it a promising candidate for a spin sink or in spin current detection applications. In order to investigate the coexistence of high mobility and strong spin-orbit coupling in the thin film regime, we have grown perovskite CaIrO₃ thin films on (001) SrTiO₃ substrates via pulsed laser deposition. X-ray diffraction measurements verify epitaxial growth on the substrate. The presence of clear Laue oscillations and typical omega-rocking curve full width half maximum values of ∼0.03° indicate high crystalline quality. Our CaIrO₃ films show semi-metallic behavior between 2-300K with ∂ρ/∂T <0 between 300-150K, and ∂ρ/∂T >0 down to low temperatures. Typical resistivity values for our films are on the order of a few mΩcm at room temperature,  comparable to bulk values. Preliminary Hall effect measurements show electron conduction across the entire temperature range. Transport measurements in high fields out of plane to the film show a weak positive magnetoresistance at low temperatures.