Structural Distortion-Induced Magnetoelastic Locking in Sr₂IrO₄ Revealed through Nonlinear Optical Harmonic Generation

Authors

D. H. Torchinsky, California Institute of Technology
H. Chu, California Institute of Technology
L. Zhao, California Institute of Technology
N. B. Perkins, University of Minnesota
Y. Sizyuk, University of Minnesota
T. Qi, University of Kentucky
Gang Cao, University of KentuckyFollow
D. Hsieh, California Institute of Technology

Abstract

We report a global structural distortion in Sr₂IrO₄ using spatially resolved optical second and third harmonic generation rotational anisotropy measurements. A symmetry lowering from an I4₁/acd to I4₁/a space group is observed both above and below the Néel temperature that arises from a staggered tetragonal distortion of the oxygen octahedra. By studying an effective superexchange Hamiltonian that accounts for this lowered symmetry, we find that perfect locking between the octahedral rotation and magnetic moment canting angles can persist even in the presence of large noncubic local distortions. Our results explain the origin of the forbidden Bragg peaks recently observed in neutron diffraction experiments and reconcile the observations of strong tetragonal distortion and perfect magnetoelastic locking in Sr₂IrO₄.

Document Type

Article

Publication Date

3-6-2015

Notes/Citation Information

Published in Physical Review Letters, v. 114, no. 9, article 096404, p. 1-5.

©2015 American Physical Society

The copyright holder has granted permission for posting the article here.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1103/PhysRevLett.114.096404

Funding Information

D. H. acknowledges support by the U.S. Army Research Office under Grant No. W911NF-13-1-0059. Instrumentation for the NHG-RA setup was partially supported by a U.S. Army Research Office DURIP Award under Grant No. W911NF-13-1-0293. D. H. acknowledges funding provided by the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center (PHY-1125565) with support of the Gordon and Betty Moore Foundation through Grant No. GBMF1250. N. P. and Y. S. acknowledge NSF support via Grants No. DMR-1255544 and No. DMR-1005932. G. C. acknowledges NSF support via Grant No. DMR-1265162.

Repository Citation

Torchinsky, D. H.; Chu, H.; Zhao, L.; Perkins, N. B.; Sizyuk, Y.; Qi, T.; Cao, Gang; and Hsieh, D., "Structural Distortion-Induced Magnetoelastic Locking in Sr₂IrO₄ Revealed through Nonlinear Optical Harmonic Generation" (2015). Physics and Astronomy Faculty Publications. 337.
https://uknowledge.uky.edu/physastron_facpub/337