The electronic structure of the high-symmetry perovskite iridate Ba sub(2)lrO sub(4)

We report angle-resolved photoemission (ARPES) measurements, density functional and model tight-binding calculations on Ba sub(2)IrO sub(4) (Ba-214), an antiferromagnetic (T sub(N) = 230 K) insulator. Ba-214 does not exhibit the rotational distortion of the IrO sub(6) octahedra that is present in its sister compound Sr sub(2)IrO sub(4) (Sr-214), and is therefore an attractive reference material to study the electronic structure of layered iridates. We find that the band structures of Ba-214 and Sr-214 are qualitatively similar, hinting at the predominant role of the spin-orbit interaction in these materials. Temperature-dependent ARPES data show that the energy gap persists well above T sub(N), and favor a Mott over a Slater scenario for this compound.