Temperature- and Magnetic-Field-Dependent Optical Properties of Heavy Quasiparticles in YbIr2Si2

TL;DR

This study investigates how temperature and magnetic fields influence the optical properties of heavy quasiparticles in YbIr2Si2, revealing the formation of a coherent heavy quasiparticle state and its suppression under magnetic fields.

Contribution

It provides the first detailed analysis of the temperature and magnetic field dependence of optical conductivity in YbIr2Si2, highlighting the behavior of heavy quasiparticles and their mass enhancement.

Findings

Heavy quasiparticle formation below T_K observed

Magnetic field reduces effective mass by about 12%

Optical conductivity fits well with a modified Drude model

Abstract

We report the temperature- and magnetic-field-dependent optical conductivity spectra of the heavy electron metal YbIr$_2$Si$_2$. Upon cooling below the Kondo temperature ($T_{\rm K}$), we observed a typical charge dynamics that is expected for a formation of a coherent heavy quasiparticle state. We obtained a good fitting of the Drude weight of the heavy quasiparticles by applying a modified Drude formula with a photon energy dependence of the quasiparticle scattering rate that shows a similar power-law behavior as the temperature dependence of the electrical resistivity. By applying a magnetic field of 6T below $T_{\rm K}$, we found a weakening of the effective dynamical mass enhancement by about 12% in agreement with the expected decrease of the $4f$-conduction electron hybridization on magnetic field.