LAUSR

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.