Spectral scaling and quantum critical behaviour in the pseudogap Anderson model

TL;DR

This paper investigates the quantum critical behavior of the pseudogap Anderson model, revealing universal spectral scaling and non-Fermi liquid properties at the quantum critical point using the local moment approach.

Contribution

It provides analytical results for the universal scaling spectra near the quantum critical point of the pseudogap Anderson model, highlighting non-Fermi liquid behavior.

Findings

Low-energy scale vanishes at the QCP.

Universal scaling spectra are analytically derived.

Spectrum at QCP shows non-Fermi liquid characteristics.

Abstract

The pseudogap Anderson impurity model provides a classic example of an essentially local quantum phase transition. Here we study its single-particle dynamics in the vicinity of the symmetric quantum critical point (QCP) separating generalized Fermi liquid and local moment phases, via the local moment approach. Both phases are shown to be characterized by a low-energy scale that vanishes at the QCP; and the universal scaling spectra, on all energy scales, are obtained analytically. The spectrum precisely at the QCP is also obtained; its form showing clearly the non-Fermi liquid, interacting nature of the fixed point.