Layered perovskite iridate ${\mathrm{Sr}}_2{\mathrm{IrO}}_4$ shares many similarities with high $T_{\text{c}}$ cuprates and is expected to host novel superconductivity but has never been realized experimentally. Despite the similarities, the prominent ${\mathrm{IrO}}_6$ octahedral rotations and sizable net canted antiferromagnetic moments lying in each ${\mathrm{IrO}}_2$ plane in ${\mathrm{Sr}}_2{\mathrm{IrO}}_4$ are strikingly different from high $T_{\text{c}}$ 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- and 2-unit-cell-thick ${\mathrm{SrIrO}}_3$ films, providing ideal single- and bilayer analogies of high $T_{\text{c}}$ cuprates.

• Received 19 June 2019
• Revised 23 October 2019
• Accepted 14 January 2020
• Corrected 8 May 2020

DOI:https://doi.org/10.1103/PhysRevB.101.085101