Microwave conductivity of heavy fermions in UPd2Al3

TL;DR

This study uses broadband microwave spectroscopy to investigate the low-energy electronic correlations in the heavy-fermion compound UPd2Al3, revealing a full Drude response and a relaxation time up to 50 ps, linked to mass enhancement.

Contribution

First detailed microwave conductivity measurements of UPd2Al3 across a broad frequency and temperature range, demonstrating the relationship between mass enhancement and relaxation time in heavy fermions.

Findings

Full Drude response observed with relaxation times up to 50 ps

Relaxation rate scales with dc resistivity as a function of temperature

No frequency-dependent relaxation rate detected within the studied range

Abstract

Heavy-fermion compounds are characterized by electronic correlation effects at low energies which can directly be accessed with optical spectroscopy. Here we present detailed measurements of the frequency- and temperature-dependent conductivity of the heavy-fermion compound UPd2Al3 using broadband microwave spectroscopy in the frequency range 45 MHz to 40 GHz at temperatures down to 1.7 K. We observe the full Drude response with a relaxation time up to 50 ps, proving that the mass enhancement of the heavy charge carriers goes hand in hand with an enhancement of the relaxation time. We show that the relaxation rate as a function of temperature scales with the dc resistivity. We do not find any signs of a frequency-dependent relaxation rate within the addressed frequency range.