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arXiv · 2203.13102

Magnetic Excitations in Square Lattice Iridates: Contrast between Ba$_2$IrO$_4$ and Sr$_2$IrO$_4$

J. P. Clancy·H. Gretarsson·A. Lupascu·J. A. Sears·Z. Nie·M. H. Upton·Jungho Kim·Z. Islam·M. Uchida·D. G. Schlom·K. M. Shen·Young-June Kim
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Abstract

We report a resonant inelastic x-ray scattering (RIXS) investigation of ultra-thin epitaxial films of Ba$_2$IrO$_4$, and compare their low energy magnetic and spin-orbit excitations to those of their sister compound Sr$_2$IrO$_4$. Due to the 180$^\circ$ Ir-O-Ir bond, the bandwidth of the magnon and spin-orbiton is significantly larger in Ba$_2$IrO$_4$, making it difficult to describe these two types of excitations as separate well-defined quasiparticles. Both types of excitations are found to be quite sensitive to the effect of epitaxial strain. In addition, we find that the d-level inversion observed in Sr$_2$IrO$_4$ is absent in Ba$_2$IrO$_4$, as predicted in recent theoretical studies. Our results illustrate that the magnetic properties of Ba$_2$IrO$_4$ are substantially different from those of Sr$_2$IrO$_4$, suggesting that these materials need to be examined more carefully with electron itinerancy taken into account.

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J. P. Clancy, H. Gretarsson, A. Lupascu, J. A. Sears, Z. Nie, M. H. Upton, Jungho Kim, Z. Islam, M. Uchida, D. G. Schlom, K. M. Shen, Young-June Kim. 2022-03-24. Magnetic Excitations in Square Lattice Iridates: Contrast between Ba$_2$IrO$_4$ and Sr$_2$IrO$_4$. https://arxiv.org/abs/2203.13102

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