Sr2IrO4 is an archetypal spin-orbit-coupled Mott insulator and has been extensively studied in part because of a wide range of predicted novel states. Limited experimental characterization of these states thus far brings to light the extraordinary susceptibility of the physical properties to the lattice, particularly, the Ir-O-Ir bond angle. Here, we report a newly observed microscopic rotation of the IrO6 octahedra below 50~K measured by single crystal neutron diffraction. This sharp lattice anomaly provides keys to understanding the anomalous low-temperature physics and a direct confirmation of a crucial role that the Ir-O-Ir bond angle plays in determining the ground state. Indeed, as also demonstrated in this study, applied electric current readily weakens the antiferromagnetic order via the straightening of the Ir-O-Ir bond angle, highlighting that even slight change in the local structure can disproportionately affect the physical properties in the spin-orbit-coupled system.
@article{arxiv.2008.12355,
title = {Pseudospin-lattice coupling and electric control of the square-lattice iridate Sr2IrO4},
author = {Feng Ye and Christina Hoffmann and Wei Tian and Hengdi Zhao and G. Cao},
journal= {arXiv preprint arXiv:2008.12355},
year = {2020}
}