Local Raman Spectroscopy of Chiral Majorana Edge Modes in Kitaev Spin Liquids and Topological Superconductors

TL;DR

This paper theoretically analyzes local Raman scattering from Majorana edge modes in Kitaev spin liquids and topological superconductors, revealing distinct spectral behaviors linked to their dimensional origins.

Contribution

It uncovers how the Raman spectra of Majorana edge modes differ between Kitaev spin liquids and topological superconductors due to their electromagnetic coupling.

Findings

Raman spectrum in Kitaev spin liquids scales as ω^3 at low energy.

Topological superconductors show a gapped Raman spectrum.

Estimate of Raman scattering intensity for α-RuCl₃ provided.

Abstract

The Raman scattering with local optical excitation from the Majorana edge modes of Kitaev spin liquids and topological superconductors is studied theoretically. Although the effective one-dimensional model is common between these two cases, the coupling to the electromagnetic field is different. It is found that the Raman spectrum at low energy scales with $\omega^3$ in Kitaev spin liquids while it shows the gap in topological superconductors. This is in sharp contrast to the infrared absorption, where the spectrum shows the gap in Kitaev spin liquids, while it behaves as $\sim \omega^2$ in topological superconductors. This indicates that the electrodynamics of Majorana edge modes depends on their higher-dimensional origins. The realistic estimate of the Raman scattering intensity is given for $\alpha$-RuCl$_3$ as the candidate for Kitaev spin liquid.