Orbital dichotomy of Fermi liquid properties in Sr$_2$RuO$_4$ revealed by Raman spectroscopy

TL;DR

This study uses polarization-resolved Raman spectroscopy to reveal orbital-dependent Fermi liquid behavior in Sr₂RuO₄, showing that different orbitals exhibit distinct quasiparticle scattering and mass properties, highlighting orbital dichotomy.

Contribution

It demonstrates the orbital dependence of Fermi liquid properties in Sr₂RuO₄ using Raman spectroscopy, revealing a dichotomy between $d_{xz/yz}$ and $d_{xy}$ orbitals.

Findings

Quasiparticle scattering rate follows $^2$ dependence.

Orbital-dependent polarization effects observed.

Fermi liquid behavior more robust in $d_{xz/yz}$ orbitals.

Abstract

We report a polarization-resolved Raman spectroscopy study of the orbital dependence of the quasiparticles properties in the prototypical multi-band Fermi liquid Sr\textsubscript{2}RuO\textsubscript{4}. We show that the quasiparticle scattering rate displays $\omega^{2}$ dependence as expected for a Fermi liquid. Besides, we observe a clear polarization-dependence in the energy and temperature dependence of the quasiparticle scattering rate and mass, with the $d_{xz/yz}$ orbital derived quasiparticles showing significantly more robust Fermi liquid properties than the $d_{xy}$ orbital derived ones. The observed orbital dichotomy of the quasiparticles is consistent with the picture of Sr\textsubscript{2}RuO\textsubscript{4} as a Hund's metal. Our study establishes Raman scattering as a powerful probe of Fermi liquid properties in correlated metals.