Free-carrier dynamics in Au2Pb probed by optical conductivity measurements.

We measured the optical reflectivity of the Dirac material Au2Pb 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 [Formula: see text] eV. Overall, optical response of Au2Pb is typically metallic with no signs of localization and bad-metal behavior.