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arXiv · 1908.02716

Compressive-strain induced enhancement of exchange interactions and short-range magnetic order in Sr$_2$IrO$_4$ investigated by Raman spectroscopy

A. Seo·P. P. Stavropoulos·H. -H. Kim·K. Fürsich·M. Souri·J. G. Connell·H. Gretarsson·M. Minola·H. Y. Kee·B. Keimer
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Abstract

We have carried out Raman spectroscopy experiments to investigate two-magnon excitations in epitaxial thin films of the quasi-two-dimensional antiferromagnetic Mott insulator Sr$_2$IrO$_4$ under in-plane misfit strain. With in-plane biaxial compression, the energy of the two-magnon peak increases, and the peak remains observable over a wider temperature range above the Néel temperature, indicating strain-induced enhancement of the superexchange interactions between $\it{J}_{eff}$ = 1/2 pseudospins. From density functional theory calculations, we have found an increase of the nearest-neighbor hopping parameter and exchange interaction with increasing biaxial compressive strain, in agreement with the experimental observations. Our experimental and theoretical results provide perspectives for systematic, theory-guided strain control of the primary exchange interactions in 5$\it{d}$ transition metal oxides.

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A. Seo, P. P. Stavropoulos, H. -H. Kim, K. Fürsich, M. Souri, J. G. Connell, H. Gretarsson, M. Minola, H. Y. Kee, B. Keimer. 2019-08-07. Compressive-strain induced enhancement of exchange interactions and short-range magnetic order in Sr$_2$IrO$_4$ investigated by Raman spectroscopy. https://doi.org/10.1103/physrevb.100.165106

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