High-Mobility Carriers in Epitaxial IrO<sub>2</sub> Films Grown using Hybrid Molecular Beam Epitaxy.

Nair, Sreejith; Yang, Zhifei; Storr, Kevin; Jalan, Bharat · Nano Lett · 2024

basic_science · Level V

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Abstract

Binary rutile oxides of 5d metals such as IrO<sub>2</sub> stand out in comparison to their 3d and 4d counterparts due to limited experimental studies, despite rich predicted quantum phenomena. Here, we investigate the electrical transport properties of IrO<sub>2</sub> by engineering epitaxial thin films grown using hybrid molecular beam epitaxy. Our findings reveal phonon-limited carrier transport and thickness-dependent anisotropic in-plane resistance in IrO<sub>2</sub> (110) films, the latter suggesting a complex relationship between strain relaxation and orbital hybridization. Magnetotransport measurements reveal a previously unobserved nonlinear Hall effect. A two-carrier analysis of this effect shows the presence of minority carriers with mobility exceeding 3000 cm<sup>2</sup>/(V s) at 1.8 K. These results point toward emergent properties in 5d metal oxides that can be controlled using dimensionality and epitaxial strain.