Dangling bonds and magnetism of grain boundaries in graphene

TL;DR

This study investigates the atomic structure and magnetic properties of grain boundaries with dangling bonds in graphene, revealing that certain defect structures are magnetic and retain magnetism after hydrogenation.

Contribution

It combines atomistic simulations and density functional calculations to identify stable defect structures and analyze their magnetic behavior in graphene grain boundaries.

Findings

The 5-8-7 defect is a common low-energy structure in DBGB.

The 5-8-7 defect exhibits magnetic properties.

Magnetism persists after hydrogenation and out-of-plane deformations.

Abstract

Grain boundaries with dangling bonds (DBGB) in graphene are studied by atomistic Monte Carlo and molecular dynamics simulations in combination with density functional (SIESTA) calculations. The most stable configurations are selected and their structure is analyzed in terms of grain boundary dislocations. It is shown that the grain boundary dislocation with the core consisting of pentagon, octagon and heptagon (5-8-7 defect) is a typical structural element of DBGB with relatively low energies. Electron energy spectrum and magnetic properties of the obtained DBGB are studied by density functional calculations. It is shown that the 5-8-7 defect is magnetic and that its magnetic moment survives after hydrogenation. The effects of hydrogenation and of out of plane deformations on the magnetic properties of DBGB are studied.