%0 Journal Article %A Boseggia, S %A Springell, R %A Walker, HC %A Ronnow, HM %A Rueegg, C %A Okabe, H %A Isobe, M %A Perry, RS %A Collins, SP %A McMorrow, DF %D 2013 %F discovery:10134049 %I AMER PHYSICAL SOC %J Physical Review Letters %N 11 %T Robustness of Basal-Plane Antiferromagnetic Order and the J(eff)=1/2 State in Single-Layer Iridate Spin-Orbit Mott Insulators %U https://discovery.ucl.ac.uk/id/eprint/10134049/ %V 110 %X The magnetic structure and electronic ground state of the layered perovskite Ba 2 IrO 4 have been investigated using x-ray resonant magnetic scattering. Our results are compared with those for Sr 2 IrO 4 , for which we provide supplementary data on its magnetic structure. We find that the dominant, long-range antiferromagnetic order is remarkably similar in the two compounds and that the electronic ground state in Ba 2 IrO 4 , deduced from an investigation of the x-ray resonant magnetic scattering L 3 / L 2 intensity ratio, is consistent with a J eff = 1 / 2 description. The robustness of these two key electronic properties to the considerable structural differences between the Ba and Sr analogues is discussed in terms of the enhanced role of the spin-orbit interaction in 5 d transition metal oxides. %Z This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.