Lattice dynamics and structural transition of the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$ investigated by high-pressure Raman scattering

Abstract

We report a polarized Raman scattering study of the lattice dynamics of $\beta$-Li${}_2$IrO${}_3$ under hydrostatic pressures up to 7.62 GPa. At ambient pressure, $\beta$-Li${}_2$IrO${}_3$ exhibits the hyperhoneycomb crystal structure and a magnetically ordered state of spin-orbit entangled Jeff = 1/2 moments that is strongly influenced by bond-directional (Kitaev) exchange interactions. At a critical pressure of ~ 4.1 GPa, the phonon spectrum changes abruptly consistent with the reported structural transition into a monoclinic, dimerized phase. A comparison to the phonon spectra obtained from density functional calculations shows reasonable overall agreement. The calculations also indicate that the high-pressure phase is a nonmagnetic insulator driven by the formation of Ir-Ir dimer bonds. Our results thus indicate a strong sensitivity of the electronic properties of $\beta$-Li${}_2$IrO${}_3$ to the pressure-induced structural transition.

16 pages, 7 figures, 5 tables, Supplemental Material included

References in corpus (14)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Quantum Monte Carlo Impurity Solver for Cluster DMFT and Electronic Structure Calculations in Adjustable Base
• Models and Materials for Generalized Kitaev Magnetism
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Hyper-honeycomb iridate $\beta$-Li2IrO3 as a platform for Kitaev magnetism
• Long range magnetic ordering in Na${}_2$IrO${}_3$
• Non-coplanar and counter-rotating incommensurate magnetic order stabilized by Kitaev interactions in $\gamma$-Li2IrO3
• Unconventional magnetic order on the hyperhoneycomb Kitaev lattice in $\beta$-Li2IrO3: full solution via magnetic resonant x-ray diffraction
• Raman spectroscopic signature of fractionalized excitations in the harmonic-honeycomb iridates $\beta$- and $\gamma$-Li${}_2$IrO${}_3$
• Unified theory of spiral magnetism in the harmonic-honeycomb iridates α, β, γ Li2IrO3
• Revealing frustrated local moment model for pressurized hyperhoneycomb iridate: paving a way toward quantum spin liquid
• High-pressure versus isoelectronic doping effect on the honeycomb iridate Na${}_2$IrO${}_3$
• Optical signature of the pressure-induced dimerization in the honeycomb iridate $\alpha$-Li${}_2$IrO${}_3$

Cited by in corpus (1)

• Interplay of magnetism and dimerization in pressurized Kitaev material $\beta$-Li${}_2$IrO${}_3$