Consequences of the local spin self-energy approximation on the heavy Fermion quantum phase transition

TL;DR

This paper demonstrates that the local spin self-energy approximation in EDMFT causes a first order quantum phase transition in the periodic Anderson model, with a coexistence region between paramagnetic and antiferromagnetic phases.

Contribution

It reveals the impact of the local spin self-energy approximation on the nature of the quantum phase transition in heavy fermion systems.

Findings

First order phase transition persists down to T=0.

Finite coexistence region of paramagnetic and AFM phases.

Transition lines differ by an electron-hole bubble at the AFM wave vector.

Abstract

We show, using the periodic Anderson model, that the local spin self-energy approximation, as implemented in the extended dynamical mean field theory (EDMFT), results in a first order phase transition which persists to T=0. Around the transition, there is a finite coexistence region of the paramagnetic and antiferromagnetic (AFM) phases. The region is bounded by two critical transition lines which differ by an electron-hole bubble at the AFM ordering wave vector.