Robustness of Basal-Plane Antiferromagnetic Order and theJeff=1/2State in Single-Layer Iridate Spin-Orbit Mott Insulators

Abstract

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 5d transition metal oxides.

Magnetic ground state ofSr2IrO4and implications for second-harmonic generation

“…One of the key experimental evidences leading to the octahedral Kramers doublet was the absence of magnetic RXS intensity at the Ir L 2 edge for reflections that showed a big resonant intensity at the L 3 edge [9,19]. This feature has been confirmed in several other nonstoichiometric compounds [19,45,46].…”

“…This feature has been confirmed in several other nonstoichiometric compounds [19,45,46]. Initially interpreted as definitive evidence for this Kramers doublet [9], the absence of a magnetic signal at the L 2 edge was considered as inconclusive, because an in-plane magnetic moment could lead to the same conclusion [43] even if the octahedral limit was not realized.…”

“…They differ by the order of the ferromagnetic in-plane component along the b-axis. Iridium atoms are labelled as in Table I. + + ++ structure has been identified as the magnetic structure of Sr 2 IrO 4 in a magnetic field (H ≥ 0.3 T) directed in the ab-plane [9,19] and also suggested as the magnetic structure in Rh-doped samples [10,11]. The −+−+ magnetic structure has not been suggested in the literature up to now, but we claim that it can describe some of the experimental results on Rh-doped samples, as detailed below [12].…”

Evolution of competing magnetic order in theJeff=1/2insulating state ofSr2Ir1−xCalder1, Kim2, Cao3 et al. 2015Phys. Rev. B423550View full textAdd to dashboardCite

“…The result is a magnetic J eff =1/2 SOC Mott-like insulating state. Experimental evidence was initially reported in Sr 2 IrO 4 4 , followed by an increasing number of Ir 4+ based transition metal oxides [5][6][7][8][9] . The role of magnetism and lattice effects, notably the existence of the J eff =1/2 state despite significant noncubic distortions, have continued to prompt debate as to the nature of the ground state and subsequent emergent properties.…”

The contribution of Diamond Light Source to the study of strongly correlated electron systems and complex magnetic structures

“…Much of the experimental effort has focused on the attempt to confirm the existence of the J eff = [78,79] determined the magnetic structure of Sr 3 Ir 2 O 7 by REXS and also imaged the magnetic domains, which were found to be of the order of 100 µm. The work of the McMorrow group on the single-layer materials focused on exploring the robustness of the conclusion that these systems are representative of the J eff = 1 2 state, traditionally inferred from the L 2 /L 3 branching ratio for different spin directions and in the presence of significant lattice distortions [80,81]. One important result they obtained is that the possibility of observing the J eff = 1 2 state by REXS is limited to specific states, i.e.…”