Pressure-driven collapse of the relativistic electronic ground state in a honeycomb iridate

Abstract

The electronic ground state in many iridate materials is described by a complex wave-function in which spin and orbital angular momenta are entangled due to relativistic spin-orbit coupling (SOC). Such a localized electronic state carries an effective total angular momentum of $J_{eff}=1/2$. In materials with an edge-sharing octahedral crystal structure, such as the honeycomb iridates Li2IrO3 and Na2IrO3, these $J_{eff}=1/2$ moments are expected to be coupled through a special bond-dependent magnetic interaction, which is a necessary condition for the realization of a Kitaev quantum spin liquid. However, this relativistic electron picture is challenged by an alternate description, in which itinerant electrons are confined to a benzene-like hexagon, keeping the system insulating despite the delocalized nature of the electrons. In this quasi-molecular orbital (QMO) picture, the honeycomb iridates are an unlikely choice for a Kitaev spin liquid. Here we show that the honeycomb iridate Li2IrO3 is best described by a $J_{eff}=1/2$ state at ambient pressure, but crosses over into a QMO state under the application of small (~ 0.1 GPa) hydrostatic pressure. This result illustrates that the physics of iridates is extremely rich due to a delicate balance between electronic bandwidth, spin-orbit coupling, crystal field, and electron correlation.

arXiv comment7 pages, 5 figures, additional supplemental material included

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Cited by in corpus (26)

• Kitaev quantum spin liquid - concept and materialization
• Mott Transition and Superconductivity in Quantum Spin Liquid Candidate NaYbSe${}_2$
• Revisiting the Kitaev material candidacy of Ir4+ double perovskite iridates
• Pressure-induced collapse of spin-orbital Mott state in the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$
• Structural, electronic, and magnetic properties of nearly-ideal $J_{\mathrm{eff}}$ $=$ 1/2 iridium halides
• Kitaev magnetism through the prism of lithium iridate
• Nearly itinerant electronic groundstate in the intercalated honeycomb iridate Ag${}_3$LiIr${}_2$O${}_6$
• Complex pressure-temperature structural phase diagram of honeycomb iridate Cu${}_2$IrO${}_3$
• Mechanism of the insulator-to-metal transition and superconductivity in the spin liquid candidate NaYbSe${}_2$ under pressure
• Electronic and magnetic properties of iridium ilmenites $A$IrO${}_3$ ($A=$ Mg, Zn, and Mn)
• Magnon-spinon dichotomy in the Kitaev hyperhoneycomb $\beta$-Li${}_2$IrO${}_3$
• Pressure-induced formation of rhodium zigzag chains in the honeycomb rhodate Li${}_2$RhO${}_3$
• Spin liquid in twisted homobilayers group-VI gichalcogenides
• Spin-orbital excitons and their potential condensation in pentavalent iridates
• Interplay of magnetism and dimerization in pressurized Kitaev material $\beta$-Li${}_2$IrO${}_3$
• First demonstration of tuning between the Kitaev and Ising limits in a honeycomb lattice
• Symmetry-protected topological magnons in three dimensional Kitaev materials
• Lattice dynamics and structural transition of the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$ investigated by high-pressure Raman scattering
• Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu${}_2$IrO${}_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis
• Spin-lattice and electron-phonon coupling in 3$d$/5$d$ hybrid Sr${}_3$NiIrO${}_6$
• A set-up for Hard X-ray Time-resolved Resonant Inelastic X-ray Scattering at SwissFEL
• First-principles design of the spinel iridate Ir2O4 for high-temperature quantum spin ice
• Enhanced Curie temperature and room-temperature 50-nm skyrmions achieved in hexagonal ferromagnet Mn5Ge3+x synthesized via a high-pressure method
• Novel electronic state of honeycomb iridate Cu${}_2$IrO${}_3$ at high pressure
• Pressure-dependent magnetism of the Kitaev candidate Li${}_2$RhO${}_3$
• Honeycomb lattice iridate on the verge of Mott-collapse