Phonon anomalies near the magnetostructural transition in Li2RuO3 : Raman spectroscopy and density functional theory studies

Abstract

Raman spectroscopy is used to control the kinetics of the magnetostructural transition in ${\mathrm{Li}}_{2}{\mathrm{RuO}}_{3}$ crystals from the low-temperature dimerized phase ($P{2}_{1}/m$) to the high-temperature phase ($C2/m$) at ${T}_{c}\ensuremath{\sim}550$ K accompanied by the destruction of the spin singlets on the Ru-Ru bonds. The theoretical group analysis and the results of the density functional theory calculations of the lattice dynamics were used to identify phonon modes that are sensitive to the transition. The observed anomalies in the behavior of the self-energies of such phonons near ${T}_{c}$ suggest their connection either with possible dynamic disordering of Ru atomic positions or with spin-phonon interaction.