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arXiv · 2206.11310

On the electronic ground state of two non-magnetic pentavalent honeycomb iridates

A. de la Torre·B. Zager·J. R. Chamorro·M. H. Upton·G. Fabbris·D. Haskel·D. Casa·T. M. McQueen·K. W. Plumb
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Abstract

We investigate the electronic structure of two Ir$^{5+}$ honeycomb iridates, Sr$_3$CaIr$_2$O$_9$ and NaIrO$_3$, by means of resonant x-ray techniques. We confirm that Sr$_3$CaIr$_2$O$_9$ realizes a large spin-orbit driven non-magnetic $J = 0$ singlet ground state despite sizable tetragonal distortions of Ir coordinating octahedra. On the other hand, the resonant inelastic x-ray spectra of NaIrO$_3$ are drastically different from expectations for a Mott insulator with octahedrally coordinated Ir$^{5+}$. We find that the data for NaIrO$_3$ can be best interpreted as originating from a narrow gap non-magnetic $S = 0$ band insulating ground state. Our results highlight the complex role of the ligand environment in the electronic structure of honeycomb iridates and the essential role of x-ray spectroscopy to characterize electronic ground states of insulating materials.

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A. de la Torre, B. Zager, J. R. Chamorro, M. H. Upton, G. Fabbris, D. Haskel, D. Casa, T. M. McQueen, K. W. Plumb. 2022-06-22. On the electronic ground state of two non-magnetic pentavalent honeycomb iridates. https://doi.org/10.1103/physrevmaterials.6.084406

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