Observation of an optical non-Fermi-liquid behavior in the heavy fermion state of YbRh$_{2}$Si$_{2}$

TL;DR

This study reveals non-Fermi-liquid behavior in YbRh₂Si₂ through optical measurements, showing a linear scattering rate dependence on temperature and photon energy, linked to its proximity to a quantum critical point.

Contribution

First observation of optical non-Fermi-liquid behavior in YbRh₂Si₂, demonstrating a linear scattering rate dependence indicative of quantum criticality.

Findings

Linear scattering rate dependence on temperature and photon energy

Evidence of non-Fermi-liquid behavior near quantum critical point

Optical properties consistent with heavy fermion quantum criticality

Abstract

We report far-infrared optical properties of YbRh$_{2}$Si$_{2}$ for photon energies down to 2 meV and temperatures 0.4 -- 300 K. In the coherent heavy quasiparticle state, a linear dependence of the low-energy scattering rate on both temperature and photon energy was found. We relate this distinct dynamical behavior different from that of Fermi liquid materials to the non-Fermi liquid nature of YbRh$_{2}$Si$_{2}$ which is due to its close vicinity to an antiferromagnetic quantum critical point.