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arXiv · 1604.03771

Terahertz Spin-Orbital Excitations in the paramagnetic state of multiferroic Sr$_2$FeSi$_2$O$_7$

Thuc T. Mai·C. Svoboda·M. T. Warren·T. -H. Jang·J. Brangham·Y. H. Jeong·S-W. Cheong·R. Valdés Aguilar
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Abstract

We studied the novel multiferroic material Sr$_2$FeSi$_2$O$_7$, and found 3 absorption modes above the magnetic ordering transition temperature using time-domain terahertz spectroscopy. These absorption modes can be explained as the optical transitions between the spin-orbit coupling and crystal field split 3d$^6$ Fe$^{2+}$ ground state term in this material. Consideration of the compressed tetrahedral environment of the Fe$^{2+}$ site is crucial to understand the excitations. We point out, however, discrepancies between the single-site atomic picture and the experimental results.

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Thuc T. Mai, C. Svoboda, M. T. Warren, T. -H. Jang, J. Brangham, Y. H. Jeong, S-W. Cheong, R. Valdés Aguilar. 2016-04-13. Terahertz Spin-Orbital Excitations in the paramagnetic state of multiferroic Sr$_2$FeSi$_2$O$_7$. https://doi.org/10.1103/physrevb.94.224416

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