Lattice dynamics and structural transition of the hyperhoneycomb iridate β−Li2IrO3 investigated by high-pressure Raman scattering

We report a polarized Raman scattering study of the lattice dynamics of β−Li2IrO3 under hydrostatic pressures up to 7.62 GPa. At ambient pressure, β−Li2IrO3 exhibits the hyperhoneycomb crystal structure and a magnetically ordered state of spin-orbit entangled Jeff = 1/2 moments that are strongly inf...

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Bibliographic Details
Published in:Physical review. B 2020-02, Vol.101 (5), p.1
Main Authors: Choi, Sungkyun, Kim, Heung-Sik, Kim, Hun-Ho, Krajewska, Aleksandra, Kim, Gideok, Minola, Matteo, Takayama, Tomohiro, Takagi, Hidenori, Haule, Kristjan, Vanderbilt, David, Keimer, Bernhard
Format: Article
Language:English
Subjects:
Bonding strength
Critical pressure
Crystal structure
Dimers
Dynamic structural analysis
Mathematical analysis
Phonons
Pressure
Raman spectra
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Summary:We report a polarized Raman scattering study of the lattice dynamics of β−Li2IrO3 under hydrostatic pressures up to 7.62 GPa. At ambient pressure, β−Li2IrO3 exhibits the hyperhoneycomb crystal structure and a magnetically ordered state of spin-orbit entangled Jeff = 1/2 moments that are 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 β−Li2IrO3 to the pressure-induced structural transition.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.101.054102