Engineering of octahedral rotations and electronic structure in ultrathin SrIrO3 films

Layered perovskite iridate Sr2IrO4 shares many similarities with high Tc cuprates and is expected to host novel superconductivity but has never been realized experimentally. Despite the similarities, the prominent IrO6 octahedral rotations and sizable net canted antiferromagnetic moments lying in each IrO2 plane in Sr2IrO4 are strikingly different from high Tc cuprates where the octahedral rotations and net canted moment are much smaller or negligible. Here, using reactive molecular beam epitaxy, we demonstrate that the octahedral rotations around the in-plane and out-of-plane axes in epitaxial iridate films can be suppressed step-by-step via interfacial clamping imposed by cubic substrates as the films approach the two-dimensional limit. In situ angle-resolved photoemission spectroscopy and first-principles calculations show a gapped antiferromagnetic ground state with dispersive low-lying bands in 1- A nd 2-unit-cell-thick SrIrO3 films, providing ideal single- A nd bilayer analogies of high Tc cuprates.