Robustness of Basal-Plane Antiferromagnetic Order and the J_(eff) = 1/2 State in Single-Layer Iridate Spin-Orbit Mott Insulators

摘要

The magnetic structure and electronic ground state of the layered perovskite Ba_2IrO_4 have been investigated using x-ray resonant magnetic scattering. Our results are compared with those for Ba_2IrO_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_2IrO_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 5d transition metal oxides.