Origin of the insulating state in honeycomb iridates and rhodates

Abstract

A burning question in the emerging field of spin-orbit driven insulating iridates, such as Na2IrO3 and Li2IrO3 is whether the observed insulating state should be classified as a Mott-Hubbard insulator derived from a half-filled relativistic j_eff=1/2 band or as a band insulator where the gap is assisted by spin-orbit interaction, or Coulomb correlations, or both. The difference between these two interpretations is that only for the former, strong spin-orbit coupling (lambda >~ W, where W is the band width) is essential. We have synthesized the isostructural and isoelectronic Li2RhO3 and report its electrical resistivity and magnetic susceptibility. Remarkably it shows insulating behavior together with fluctuating effective S=1/2 moments, similar to Na2IrO3 and Li2IrO3, although in Rh4+ (4d5) the spin-orbit coupling is greatly reduced. We show that this behavior has non-relativistic one-electron origin (although Coulomb correlations assist in opening the gap), and can be traced down to formation of quasi-molecular orbitals, similar to those in Na2IrO3.

7 pages, 7 figures

References in corpus (10)

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• Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5$d$ Transition Metal Oxides Sr${}_{n+1}$Ir${}_n$O${}_{3n+1}$ ($n$=1, 2, and $\infty$)
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• Na2IrO3 as a molecular orbital crystal
• Li${}_2$RhO${}_3$: A spin-glassy relativistic Mott insulator
• Accounting for spin fluctuations beyond LSDA in the density functional theory

Cited by in corpus (44)

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• Clues and criteria for designing Kitaev spin liquid revealed by thermal and spin excitations of honeycomb iridates Na${}_2$IrO${}_3$
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• Honeycomb Layered Oxides: Structure, Energy Storage, Transport, Topology and Relevant Insights
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• Highly anisotropic magnon dispersion in Ca2RuO4: evidence for strong spin orbit coupling
• Local Magnetism and Spin Dynamics of the Frustrated Honeycomb Rhodate Li2RhO3
• Emergent ultrafast phenomena in correlated oxides and heterostructures
• From a quasimolecular band insulator to a relativistic Mott insulator in $t_{2g}^5$ systems with a honeycomb lattice structure
• High-pressure versus isoelectronic doping effect on the honeycomb iridate Na${}_2$IrO${}_3$
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• Robust singlet dimers with fragile ordering in two-dimensional honeycomb lattice of Li${}_2$RuO${}_3$
• Magnetic anisotropy of the alkali iridate Na${}_2$IrO${}_3$ at high magnetic fields: evidence for strong ferromagnetic Kitaev correlations
• Analysis of the optical conductivity for A2IrO3 (A = Na, Li) from first principles
• Kitaev Quantum Spin Liquids
• Two-dimensional heavy fermions on the strongly correlated boundaries of Kondo topological insulators
• Computational Study of the Magnetic Structure of Na${}_2$IrO${}_3$
• Direct detection of dimer orbitals in Ba${}_5$AlIr${}_2$O${}_{11}$
• Nearly itinerant electronic groundstate in the intercalated honeycomb iridate Ag${}_3$LiIr${}_2$O${}_6$
• Unusual spin dynamics in the low-temperature magnetically ordered state of Ag${}_3$LiIr${}_2$O${}_6$
• Successive spin-flop transitions of Neel-type antiferromagnet Li${}_2$MnO${}_3$ single crystal with honeycomb-lattice
• Anisotropic Quantum Spin Hall Effect, Spin-Orbital Textures and Mott Transition
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• Optical signature of the pressure-induced dimerization in the honeycomb iridate $\alpha$-Li${}_2$IrO${}_3$
• Electronic excitations and structure of Li2IrO3 thin films grown on ZrO${}_2$:Y (001) substrates
• Tracking local magnetic dynamics via high-energy charge excitations in a relativistic Mott insulator
• Pressure-induced formation of rhodium zigzag chains in the honeycomb rhodate Li${}_2$RhO${}_3$
• Introducing the monoclinic polymorph of the Kitaev magnet Na${}_2$Co${}_2$TeO${}_6$
• Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na${}_2$IrO${}_3$
• First demonstration of tuning between the Kitaev and Ising limits in a honeycomb lattice
• Large off diagonal exchange couplings and spin liquid states in ${\mathbf{C}}_3$ symmetric iridates
• The Insulating Nature of Na2IrO3: Mott-type or Slater-type?
• On the multi-$\mathbf{q}$ characteristics of magnetic ground states of honeycomb cobalt oxides
• Mott Gap Softening Coinciding with Spin Correlations Collapse in a-RuCl3
• Pressure-dependent magnetism of the Kitaev candidate Li${}_2$RhO${}_3$