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

2020/02/07 by Sungkyun Choi, Heung‐Sik Kim, Heung-Sik Kim +14
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Density functional theory #Hydrostatic pressure #Magnetic and transport properties of perovskites and related materials #Materials science #Monoclinic crystal system #Phase transition #Phonon #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Raman spectroscopy #Thermodynamics #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.101.054102

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

openalex publication_date 2020/02/07 · openalex created_date 2020/02/14 · arxiv created 2021/01/19 · arxiv updated 2021/01/20 · openalex updated_date 2026/08/06

Abstract

We report a polarized Raman scattering study of the lattice dynamics of \ensuremathβ\ensuremath-Li₂IrO₃ under hydrostatic pressures up to 7.62 GPa. At ambient pressure, \ensuremathβ\ensuremath-Li₂IrO₃ exhibits the hyperhoneycomb crystal structure and a magnetically ordered state of spin-orbit entangled J_eff = 1/2 moments that are strongly influenced by bond-directional (Kitaev) exchange interactions. At a critical pressure of \ensuremath∼\phantom\rule0.16em0ex4.1 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 \ensuremathβ\ensuremath-Li₂IrO₃ to the pressure-induced structural transition.

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