# Polarization-resolved Raman spectroscopy of {\alpha}-RuCl3 and evidence of room temperature two-dimensional magnetic scattering

## TL;DR

This study uses polarization-resolved Raman spectroscopy on {}-RuCl3 to identify phonon symmetries and evidence of 2D magnetic scattering, indicating Kitaev interactions persist at room temperature.

## Contribution

It provides the first polarization-resolved Raman analysis of {}-RuCl3, revealing phonon symmetries and evidence of 2D magnetic scattering related to Kitaev physics at room temperature.

## Key findings

- Phonon pairs show 4-fold or 2-fold polarization dependence.
- The magnetic scattering continuum disappears with perpendicular polarization.
- Kitaev interactions persist up to room temperature.

## Abstract

Polarization-resolved Raman spectroscopy was performed and analyzed from large, high quality, mono-domain single crystal of {\alpha}-RuCl3, a proximate Kitaev quantum spin liquid. Spectra were collected with laser polarizations parallel and perpendicular to the honeycomb plane. Pairs of nearly degenerate phonons were discovered and show either a 4-fold or 2-fold polarization angle dependence in their Raman intensity, thereby providing evidence to definitively assign the bulk crystal point group as C2h. The low frequency continuum that is often attributed to scattering from pairs of Majorana fermions was also examined and found to disappear when the laser excitation and scattered photon polarizations were perpendicular to the honeycomb plane. This disappearance, along with the behavior of the phonon spectrum in the same polarization configuration, strongly suggests that the scattering continuum is 2-dimensional. We argue that this scattering continuum originates from the Kitaev magnetic interactions that survives up to room temperature, a scale larger than the bare Kitaev exchange energy of approximately 50 K.