High-Mobility Carriers in Epitaxial IrO2 Films Grown using Hybrid Molecular Beam Epitaxy

Binary rutile oxides of 5d metals such as IrO2, stand out as a paradox due to limited experimental studies despite the rich predicted quantum phenomena. Here, we investigate the electrical transport properties of IrO2 by engineering epitaxial thin films grown via hybrid molecular beam epitaxy. Our findings reveal phonon-limited carrier transport and thickness-dependent anisotropic in-plane resistance in IrO2 (110) films, the latter suggesting a complex relationship between strain relaxation and orbital hybridization. Magneto-transport measurements reveal a previously unobserved non-linear Hall effect. A two-carrier analysis of this effect shows the presence of minority carriers with mobility exceeding 3000 cm2/Vs at 1.8 K. These results point towards emergent properties in 5d metal oxides that can be controlled using dimensionality and epitaxial strain.