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

2022/06/22 by de la Torre, A., Zager, B., Chamorro, J. R. +6
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el)

paper · doi:10.48550/arxiv.2206.11310

Abstract

We investigate the electronic structure of two Ir⁵⁺ honeycomb iridates, Sr₃CaIr₂O₉ and NaIrO₃, by means of resonant x-ray techniques. We confirm that Sr₃CaIr₂O₉ 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 NaIrO₃ are drastically different from expectations for a Mott insulator with octahedrally coordinated Ir⁵⁺. We find that the data for NaIrO₃ 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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