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Structural Distortion-Induced Magnetoelastic Locking in Sr_2IrO_4 Revealed through Nonlinear Optical Harmonic Generation

Torchinsky, D. H. and Chu, H. and Zhao, L. and Perkins, N. B. and Sizyuk, Y. and Qi, T. and Cao, G. and Hsieh, D. (2015) Structural Distortion-Induced Magnetoelastic Locking in Sr_2IrO_4 Revealed through Nonlinear Optical Harmonic Generation. Physical Review Letters, 114 (9). Art. No. 096404. ISSN 0031-9007. doi:10.1103/PhysRevLett.114.096404.

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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 I4_1/acd to I4_1/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 Sr_2IrO_4.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Chu, H.0000-0002-1989-9517
Hsieh, D.0000-0002-0812-955X
Alternate Title:A structural distortion induced magneto-elastic locking in Sr2IrO4 revealed through nonlinear optical harmonic generation
Additional Information:© 2015 American Physical Society. Received 10 July 2014; published 5 March 2015. We acknowledge useful discussions with Feng Ye, Bryan Chakoumakos, Stephen Lovesey, Dmitry Khalyavin, Peter Woelfle and Stephen Wilson. 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.
Group:Institute for Quantum Information and Matter
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-13-1-0059
Army Research Office (ARO)W911NF-13-1-0293
Gordon and Betty Moore FoundationGBMF1250
Institute for Quantum Information and Matter (IQIM)UNSPECIFIED
Issue or Number:9
Record Number:CaltechAUTHORS:20141117-101456748
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51833
Deposited By: Ruth Sustaita
Deposited On:17 Nov 2014 21:06
Last Modified:10 Nov 2021 19:16

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