Non-Fermi liquid behaviour from dynamical effects of impurity scattering in correlated Fermi liquids

TL;DR

This paper investigates how impurity scattering induces non-Fermi liquid behavior in correlated Fermi liquids, revealing a linear frequency dependence in scattering rates and a disorder-driven crossover from coherent to impurity-dominated regimes.

Contribution

It provides a theoretical framework showing how dynamical impurity effects lead to non-Fermi liquid behavior and predicts observable signatures in resistivity and optical conductivity.

Findings

Linear in frequency scattering rate due to disorder

Disappearance of Drude peak beyond critical disorder p_c

Significant non-Fermi liquid effects only in certain regimes

Abstract

The interplay of disorder and interactions is a subject of perennial interest. In this work, we have investigated the effect of disorder due to chemical substitution on the dynamics and transport properties of correlated Fermi liquids. A low frequency analysis in the concentrated and dilute limits shows that the dynamical local potentials arising through disorder averaging generate a linear (in frequency) term in the scattering rate. Such non-Fermi liquid behaviour (nFL) is investigated in detail for Kondo hole substitution in heavy fermions within dynamical mean field theory. We find closed form expressions for the dependence of the static and linear terms in the scattering rate on substitutional disorder and model parameters. We argue that the low temperature resistivity will acquire a linear in temperature term, and show that the Drude peak structure in the optical conductivity will disappear beyond a certain disorder $p_c$, that marks the crossover from lattice coherent to single-impurity behaviour. A full numerical solution of the DMFT equations reveals that the nFL term will show up significantly only in certain regimes, although it is present for any non-zero disorder concentration in principle. We highlight the dramatic changes that occur in the quasiparticle scattering rate in the proximity of $p_c$. Remarkably, we find that the nFL behaviour due to dynamical effects of impurity scattering has features that are distinct from those arising through Griffiths singularities or distribution of Kondo scales. Relevance of our findings to experiments on alloyed correlated systems is pointed out.