  5d iridates have shown vast emergent phenomena due to a strong interplay
among its lattice, charge and spin degrees of freedom, because of which the
potential in spintronic application of the thin-film form is highly leveraged.
Here we have epitaxially stabilized perovskite SrIr$_{0.8}$Sn$_{0.2}$O$_3$ on
[001] SrTiO$_3$ substrates through pulsed laser deposition and systematically
characterized the structural, electronic and magnetic properties. Physical
properties measurements unravel an insulating ground state with a weak
ferromagnetism in the compressively strained epitaxial film. The octahedral
rotation pattern is identified by synchrotron x-ray diffraction, resolving a
mix of $a^+b^-c^-$ and $a^-b^+c^-$ domains. X-ray magnetic resonant scattering
directly demonstrates a G-type antiferromagnetic structure of the magnetic
order and the spin canting nature of the weak ferromagnetism.
