Rientrant metallicity in the Hubbard model: the case of honeycomb nanoribbons

TL;DR

This study uses cluster perturbation theory to analyze how electron-electron interactions affect the electronic properties of honeycomb nanoribbons, revealing unexpected semimetallic behavior at moderate interactions.

Contribution

It provides the first detailed quasiparticle band structures of honeycomb nanoribbons considering electron-electron interactions at various strengths.

Findings

Armchair nanoribbons show semimetallic behavior at moderate U

Insulating character recovers only at larger U values

Electron interactions significantly alter nanoribbon electronic properties

Abstract

Based on the Cluster Perturbation solution of the Hubbard hamiltonian for a 2-D honeycomb lattice we present quasiparticle band structures of nanoribbons at half filling as a function of the on-site electron-electron repulsion. We show that at moderate values of e-e interaction ribbons with armachair shaped edges exhibit an unexpected semimetallic behavior, recovering the original insulating character only at larger values of $U$.