Electron Correlation Driven Heavy-Fermion Formation in LiV2O4

TL;DR

This study uses optical measurements to show that strong electronic correlations and geometrical frustration drive heavy-fermion behavior in LiV2O4, a d-electron metal with unique charge dynamics.

Contribution

It reveals that heavy-fermion formation in LiV2O4 is driven by electron correlations and geometrical frustration, differing from f-electron Kondo systems.

Findings

Charge dynamics are highly incoherent above T* ~ 20 K.

Spectral weight redistributes over ~5 eV energy scales.

Heavy quasiparticle formation is linked to electronic correlations and frustration.

Abstract

Optical reflectivity measurements were performed on a single crystal of the d-electron heavy-fermion (HF) metal LiV2O4. The results evidence the highly incoherent character of the charge dynamics for all temperatures above T^* \approx 20 K. The spectral weight of the optical conductivity is redistributed over extremely broad energy scales (~ 5 eV) as the quantum coherence of the charge carriers is recovered. This wide redistribution is, in sharp contrast to f-electron Kondo lattice HF systems, characteristic of a metallic system close to a correlation driven insulating state. Our results thus reveal that strong electronic correlation effects dominate the low-energy charge dynamics and heavy quasiparticle formation in LiV2O4. We propose the geometrical frustration, which limits the extension of charge and spin ordering, as an additional key ingredient of the low-temperature heavy-fermion formation in this system.