Slaving of the magnetic moment canting to the correlated oxygen rotation in Sr2IrO4 revealed by X-ray resonant scattering

TL;DR

This study uses X-ray resonant scattering to confirm that in Sr2IrO4, the magnetic moments' canting is directly linked to the correlated rotation of oxygen octahedra, supporting the $J_{eff}=1/2$ state in this Mott insulator.

Contribution

The paper provides direct experimental evidence that magnetic moment canting in Sr2IrO4 is slaved to oxygen octahedral rotation, confirming theoretical predictions about the $J_{eff}=1/2$ state.

Findings

Magnetic moments are canted by approximately 12.2 degrees.

Magnetic moment canting follows oxygen octahedral rotation.

Supports the $J_{eff}=1/2$ state in Sr2IrO4.

Abstract

Sr2IrO4 is a prototype of the class of Mott insulators in the strong spin-orbit interaction (SOI) limit described by a $J_{\mathrm{eff}}=1/2$ ground state. In Sr2IrO4, the strong SOI is predicted to manifest itself in the slaving of the canting of the magnetic moments to the correlated rotation by 11.8(1)$^{\circ}$ of the oxygen octahedra that characterizes its distorted layered perovskite structure. Using X-ray resonant scattering at the Ir $L_3$ edge we have measured accurately the intensities of Bragg peaks arising from different components of the magnetic structure. From a careful comparison of integrated intensities of peaks due to basal-plane antiferromagnetism, with those due to b-axis ferromagnetism, we deduce a canting of the magnetic moments of 12.2(8)$^{\circ}$. We thus confirm that in Sr2IrO4 the magnetic moments rigidly follow the rotation of the oxygen octahedra, indicating that, even in the presence of significant non-cubic structural distortions, it is a close realization of the $J_{\mathrm{eff}}=1/2$ state