Fate of a multiple-band Fermi liquid that is coupled with critical $\phi^4$ bosons

TL;DR

This paper investigates how a coupled electron-hole Fermi system with critical bosonic interactions exhibits non-Fermi liquid behavior near a quantum critical point, revealing velocity renormalization and pseudo-gap features.

Contribution

It provides a one-loop renormalization group analysis of a multi-band Fermi system coupled to critical bosons, highlighting non-Fermi liquid phenomena at quantum criticality.

Findings

Fermi velocities of electron and hole bands become equal at the QCP

Density of states shows a logarithmic pseudo-gap at the QCP

System exhibits non-Fermi liquid thermodynamic and magnetic properties

Abstract

Multiple-band nature of electronic energy bands leads to novel physical effects in solids. In this paper, we clarify physical properties of a Fermi system with a pair of electron and hole Fermi surfaces (FSs), whose coupling is mediated by a critical U(1) boson field. By using a one-loop renormalization group analysis, we show that when the boson field undergoes a quantum phase transition with broken U(1) symmetry, the multiple-band Fermi system shows a non-Fermi liquid (non-FL) behaviour in its thermodynamic and magnetic properties. At a quantum critical point (QCP), Fermi velocities of the two FSs are renormalized into a same critical velocity as a boson velocity, and the fermion's density of states (DOS) shows a pseudo-gap behaviour with a logarithmic energy dependence at the QCP.