  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.
