High-pressure insulator-to-metal transition in Sr$_3$Ir$_2$O$_7$ studied by x-ray absorption spectroscopy
| Autor: | Donnerer, C., Sala, M. Moretti, Pascarelli, S., Rosa, A. D., Andreev, S. N., Mazurenko, V. V., Irifune, T., Hunter, E. C., Perry, R. S., McMorrow, D. F. |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Physical Review B 97, 035106 (2018) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.97.035106 |
| Popis: | High-pressure x-ray absorption spectroscopy was performed at the Ir $L_3$ and $L_2$ absorption edges of Sr$_3$Ir$_2$O$_7$. The branching ratio of white line intensities continuously decreases with pressure, reflecting a reduction in the angular part of the expectation value of the spin-orbit coupling operator, $\left\langle {\bf L} \cdot {\bf S} \right\rangle$. Up to the high-pressure structural transition at 53 GPa, this behavior can be explained within a single-ion model, where pressure increases the strength of the cubic crystal field, which suppresses the spin-orbit induced hybridization of $J_{\text{eff}} = 3/2$ and $e_g$ levels. We observe a further reduction of the branching ratio above the structural transition, which cannot be explained within a single-ion model of spin-orbit coupling and cubic crystal fields. This change in $\left\langle {\bf L} \cdot {\bf S} \right\rangle$ in the high-pressure, metallic phase of Sr$_3$Ir$_2$O$_7$ could arise from non-cubic crystal fields or a bandwidth-driven hybridization of $J_{\text{eff}}=1/2,\,3/2$ states, and suggests that the electronic ground state significantly deviates from the $J_{\text{eff}}=1/2$ limit. Comment: 8 pages, 5 figures |
| Databáze: | arXiv |
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