Dimensionality-driven metal-insulator transition in spin-orbit-coupled IrO2

A metal-insulator transition is observed in spin-orbit-coupled IrO2 thin films upon reduction of the film thickness. In the epitaxially grown samples, the critical thickness (t similar to 1.5-2.2 nm) is found to depend on growth orientation (001), (100) or (110). Interestingly from the applied point of view, the insulating behavior is found even in polycrystalline ultrathin films. By analyzing the experimental electrical response with various theoretical models, we find good fits to the Efros-Shklovskii-VRH and the Arrhenius-type behaviors, which suggests an important role of electron correlations in determining the electrical properties of IrO2. Our magnetic measurements also point to a significant role of magnetic order. Altogether, our results would point to a mixed Slater- and Mott-type of insulator.

Automated summary

A metal-insulator transition is observed in spin-orbit-coupled IrO2 thin films as the film thickness is reduced, with the critical thickness depending on growth orientation. The experimental electrical response fits well with Efros-Shklovskii-VRH and Arrhenius-type behaviors, indicating the importance of electron correlations. Magnetic measurements also suggest a significant role of magnetic order in the electrical properties of IrO2, pointing to a mixed Slater- and Mott-type insulator.