Optical evidence for mass enhancement of quasiparticles in pyrochlore Cd$_2$Re$_2$O$_7$

TL;DR

This study uses optical measurements to reveal mass enhancement of quasiparticles in the superconductor Cd$_2$Re$_2$O$_7$, showing an exotic metallic state with distinct optical features and moderate effective mass increase at low temperatures.

Contribution

It provides the first optical evidence of quasiparticle mass enhancement in Cd$_2$Re$_2$O$_7$, highlighting its exotic metallic behavior in the normal state.

Findings

Optical conductivity shows a zero-frequency resonance and a mid-infrared band.

Moderate effective mass enhancement at low temperature.

Exotic metallic state characterized by distinct optical features.

Abstract

We report on the results of optical studies of the newly discovered superconductor Cd$_2$Re$_2$O$_7$ in the normal state. We show that the compound has an exotic metallic state at low temperature. The optical conductivity spectrum exhibits two distinct features: a sharp renormalized resonance mode at zero frequency and a broad mid-infrared excitation band. Detailed analysis reveals a moderate enhancement of the effective mass at low temperature and low frequency.