Multipeak quasielastic light scattering and high-frequency electronic excitations in honeycomb Li$_2$RuO$_3$

TL;DR

This study investigates low-frequency Raman spectra and electronic excitations in Li$_2$RuO$_3$, revealing multipeak quasielastic scattering linked to spin fluctuations and a significant electronic structure change across the magnetostructural transition.

Contribution

It provides new insights into spin and electronic dynamics in Li$_2$RuO$_3$ through temperature-dependent Raman spectroscopy, highlighting multipeak quasielastic scattering and electronic excitation behavior.

Findings

Multipeak quasielastic scattering observed below and above transition.

Electronic excitation at 2150 cm$^{-1}$ increases below transition.

Electronic structure modification due to degeneracy removal in Ru$^{4+}$ ions.

Abstract

We measured the temperature dependence of low-frequency Raman spectra in Li$_2$RuO$_3$, and observed multipeak quasielastic scattering in the Ru honeycomb polarizations below and above the magnetostructural transition temperature. We attribute this scattering to the fluctuations of the energy density in the spin system. High-frequency electronic light scattering was observed at 2150 $cm^{-1}$. Its intensity increased significantly below the transition temperature, confirming substantial modification of electronic structure due to removal of degeneracy in $t_{2g}$-manifold of Ru$^{4+}$ ions.