  By combining 5d transition-metal oxides showing pronounced spin-orbit
interactions and oxide-based heterostructures, we propose rutile-based
IrO2/TiO2 superlattices as promising candidates for unconventional electronic
properties. By means of density-functional-theory simulations complemented with
Hubbard-like corrections, we focus on the evolution of the electronic structure
as a function of the IrO2 layer thickness and predict the heterostructures to
exhibit a thickness-controlled metal-to-insulator transition, crucially related
to the connectivity among IrO6 octahedra. The subtle interplay between electron
correlation and spin-orbit coupling leads to an almost pure Jeff = 1/2
spin-orbit insulating state at the level of atomically-thin IrO2 monolayer with
almost isolated IrO6 octahedra, leading to a predicted emerging state awaiting
for experimental confirmation.
