Magnetism and interaction-induced gap opening in graphene with vacancies or hydrogen adatoms: Quantum Monte Carlo study

TL;DR

This study uses lattice Quantum Monte Carlo methods to analyze how vacancies and hydrogen adatoms induce magnetic ordering and open energy gaps in graphene, considering realistic Coulomb interactions.

Contribution

It provides the first detailed quantum Monte Carlo analysis of interaction-induced gap opening and magnetic ordering in graphene with vacancies or adatoms.

Findings

Antiferromagnetic ordering observed around vacancies and adatoms.

Energy gaps of 0.7 eV and 1.1 eV estimated for different graphene substrates.

Long-range Coulomb interactions significantly influence electronic properties.

Abstract

We study electronic properties of graphene with finite concentration of vacancies or other resonant scatterers by a straightforward lattice Quantum Monte Carlo calculations. Taking into account realistic long-range Coulomb interaction we calculate distribution of spin density associated to midgap states and demonstrate antiferromagnetic ordering. Energy gaps are open due to the interaction effects, both in the bare graphene spectrum and in the vacancy/impurity bands. In the case of 5 % concentration of resonant scatterers the latter gap is estimated as 0.7 eV and 1.1 eV for graphene on boron nitride and freely suspended graphene, respectively.