Structural and Electronic Properties of Iridate Epitaxial Thin Films

Complex oxide materials that exhibit strong spin-orbit coupling (SOC) and electron-electron interactions have garnered attention because of their potential to stabilize topological states or produce other novel emergent phenomena. Bulk CaIrO₃ is a semimetal and exhibits strong SOC, but has also been reported to have electron mobilities as high as 60,000 cm²/Vs and predicted to harbor Dirac electrons. The combination of strong spin orbit coupling and high carrier mobility is unusual and makes CaIrO₃ an attractive material for spin current detection. We have fabricated CaIrO₃ thin films on SrTiO₃ and (LaAlO₃)_0.3(Sr₂TaAlO₆)_0.7 substrates using pulsed laser deposition, allowing for study of the material under tensile and compressive strain. Epitaxial growth, coherent epitaxial strain, and high crystalline quality were verified by X-ray diffraction, showing clear Laue oscillations and typical omega-rocking curve full width half maximum values of ∼0.03°. Resistivity values are comparable to published bulk values for CaIrO₃ with room temperature resistivity values of a few mΩcm. Initial Hall effect measurements show that electrons dominate the conduction across the temperature range 2-300K. At low temperatures weak positive magnetoresistance is observed in the presence of high out of plane fields. <br/><br/>*We acknowledge support from the National Science Foundation under grant \#2037652.