Kondo behavior in the asymmetric Anderson model: Analytic approach

TL;DR

This paper presents an analytic approach to the asymmetric Anderson model, elucidating the Kondo temperature, spectral features, and the conditions for quasiparticle resonance formation at low temperatures.

Contribution

It introduces a diagrammatic, analytically controllable method to study the asymmetric Anderson model and clarifies the relationship between Kondo temperature and spectral features.

Findings

Kondo temperature exists at any impurity filling

Resonance peak forms mainly in electron-hole symmetric cases

Satellite Hubbard bands are discussed in spectral functions

Abstract

The low-temperature behavior of the asymmetric single-impurity Anderson model is studied by diagrammatic methods resulting in analytically controllable approximations. We first discuss the ways one can simplify parquet equations in critical regions of singularities in the two-particle vertex. The scale vanishing at the critical point defines the Kondo temperature at which the electron-hole correlation function saturates. We show that the Kondo temperature exists at any filling of the impurity level. A quasiparticle resonance peak in the spectral function, however, forms only in almost electron-hole symmetric situations. We relate the Kondo temperature with the width of the resonance peak. Finally we discuss the existence of satellite Hubbard bands in the spectral function.