Free-carrier dynamics in Au$_{2}$Pb probed by optical conductivity measurements

TL;DR

This study investigates the free-carrier dynamics in the Dirac material Au₂Pb using broad-range optical conductivity measurements, revealing metallic behavior dominated by trivial bulk carriers with temperature-independent plasma frequency.

Contribution

First comprehensive optical conductivity analysis of Au₂Pb across a wide frequency and temperature range, highlighting trivial bulk carrier dominance and metallic properties.

Findings

Free-carrier contributions dominate optical conductivity.

Total plasma frequency is temperature-independent at 3.9 eV.

Material exhibits typical metallic behavior with no localization signs.

Abstract

We measured the optical reflectivity of the Dirac material Au$_{2}$Pb in a broad frequency range (30 - 48 000 cm$^{-1}$) for temperatures between 9 and 300 K. The optical conductivity, computed from the reflectivity, is dominated by free-carrier contributions from topologically trivial bulk bands at all temperatures. The temperature-independent total plasma frequency of these carriers is 3.9 $\pm$ 0.2 eV. Overall, optical response of Au$_{2}$Pb is typically metallic with no signs of localization and bad-metal behavior.