TY - JOUR VL - 110 N1 - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions. PB - AMER PHYSICAL SOC A1 - Boseggia, S A1 - Springell, R A1 - Walker, HC A1 - Ronnow, HM A1 - Rueegg, C A1 - Okabe, H A1 - Isobe, M A1 - Perry, RS A1 - Collins, SP A1 - McMorrow, DF JF - Physical Review Letters Y1 - 2013/03/13/ TI - Robustness of Basal-Plane Antiferromagnetic Order and the J(eff)=1/2 State in Single-Layer Iridate Spin-Orbit Mott Insulators AV - public N2 - 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. IS - 11 UR - https://doi.org/10.1103/PhysRevLett.110.117207 EP - 5 ID - discovery10134049 ER -