Kondo Breakdown and Hybridization Fluctuations in the Kondo-Heisenberg Lattice

TL;DR

This paper investigates the quantum critical point in the Kondo-Heisenberg lattice, revealing hybridization fluctuations with z=3 dynamical exponent and explaining non-Fermi liquid behaviors like T log T resistivity and diverging specific heat.

Contribution

It introduces a fermionic representation approach to analyze the deconfined quantum critical point, identifying distinct hybridization phases and their fluctuation effects.

Findings

Critical fluctuations exhibit z=3 dynamical exponent.

Resistivity shows T log T behavior near criticality.

Specific heat coefficient diverges logarithmically with temperature.

Abstract

We study the deconfined quantum critical point of the Kondo-Heisenberg lattice in three dimensions using a fermionic representation for the localized spins. The mean-field phase diagram exhibits a zero temperature quantum critical point separating a spin liquid phase where the hybridization vanishes and a Kondo phase where it does not. Two solutions can be stabilized in the Kondo phase, namely a uniform hybridization when the band masses of the conduction electrons and the spinons have the same sign, and a modulated one when they have opposite sign. For the uniform case, we show that above a very small temperature scale, the critical fluctuations associated with the vanishing hybridization have dynamical exponent z=3, giving rise to a resistivity that has a T log T behavior. We also find that the specific heat coefficient diverges logarithmically in temperature, as observed in a number of heavy fermion metals.