Non-Fermi Liquid behavior in Neutral Bilayer Graphene

TL;DR

This paper demonstrates that neutral bilayer graphene exhibits non-Fermi liquid behavior characterized by a linear quasiparticle decay rate and vanishing quasiparticle weight at low energies, due to its unique electronic structure.

Contribution

The study provides the first detailed calculation of the density response and self-energy in neutral bilayer graphene within RPA, revealing non-Fermi liquid properties.

Findings

Quasiparticle decay rate scales linearly with energy

Quasiparticle weight vanishes logarithmically at low energies

Distinct behavior from single-layer graphene

Abstract

We calculate the density-density response function and electron self-energy for undoped bilayer graphene, within the Random Phase Approximation (RPA). We show that the quasiparticle decay rate scales linearly with the quasiparticle energy, and quasiparticle weight vanishes logarithmically in the low-energy limit, indicating non-Fermi liquid behavior. This is a consequence of the absence of a Fermi surface for neutral bilayer graphene and corresponding larger phase space available for scattering processes. Experimental consequences of our results as well as their differences from those of single-layer graphene are discussed.