Probing Fractionalized Excitations in Kitaev Spin Liquids via Phonon Dynamics

In this talk, we present a theoretical study of phonon dynamics in quantum spin liquids, with a focus on sound attenuation and Raman scattering as experimental probes. We investigate the coupling between phonons and fractionalized excitations in extended Kitaev spin liquids in both two and three dimensions. Through Raman scattering, we analyze the temperature-dependent asymmetric Fano lineshape, demonstrating that interactions between optical phonons and a continuum of fractionalized spin excitations provide signatures of Majorana fermions and $Z_2$ fluxes. We compare our theoretical findings with experimental results from $\alpha$-RuCl$_3$ and $\beta$-Li$_2$IrO$_3$. Additionally, we calculate sound attenuation in $\alpha$-RuCl$_3$, where magnetoelastic interactions reveal phonon scattering by Majorana fermions. Our results show how temperature, magnetic field, and disorder influence phonon dynamics, providing key insights into fractionalized excitations in Kitaev materials.