Emergent Charge Fluctuations at the Kondo Breakdown of Heavy Fermions

TL;DR

This paper investigates how charge fluctuations emerge at the quantum critical point in heavy fermion systems, revealing a critical charge mode linked to Kondo singlet breakdown, with implications for experimental observations.

Contribution

It introduces a model showing a Kondo breakdown transition with emergent critical charge fluctuations at the QCP in heavy fermion materials.

Findings

Identification of a critical charge mode at the Kondo breakdown

Observation of /T scaling at the quantum critical point

Implications for experimental detection of charge fluctuations

Abstract

One of the challenges in strongly correlated electron systems, is to understand the anomalous electronic behavior that develops at an antiferromagnetic quantum critical point (QCP), a phenomenon that has been extensively studied in heavy fermion materials. Current theories have focused on the critical spin fluctuations and associated break-down of the Kondo effect. Here we argue that the abrupt change in Fermi surface volume that accompanies heavy fermion criticality leads to critical charge fluctuations. Using a model one dimensional Kondo lattice in which each moment is connected to a separate conduction bath, we show a Kondo breakdown transition develops between a heavy Fermi liquid and a gapped spin liquid via a QCP with \omega/T scaling, which features a critical charge mode directly associated with the break-up of Kondo singlets. We discuss the possible implications of this emergent charge mode for experiment.