Van der Waals interaction in magnetic bilayer graphene nanoribbons

TL;DR

This paper investigates the van der Waals interactions and magnetic properties of bilayer graphene nanoribbons using first principles calculations, revealing stability differences based on edge magnetism and ribbon width.

Contribution

It provides new insights into the magnetic and stacking stability behaviors of zigzag graphene nanoribbons considering van der Waals forces and spin polarization.

Findings

Direct stacking is more stable than Bernal in ultranarrow ribbons.

Magnetic interactions influence the stability and magnetization of the ribbons.

Zigzag bilayer ribbons remain magnetic on substrates for larger widths.

Abstract

We study the interaction energy between two graphene nanoribbons by first principles calculations, including van der Waals interactions and spin polarization. For ultranarrow zigzag nanoribbons, the direct stacking is even more stable than Bernal, competing in energy for wider ribbons. This behavior is due to the magnetic interaction between edge states. We relate the reduction of the magnetization in zigzag nanoribbons with increasing ribbon width to the structural changes produced by the magnetic interaction, and show that when deposited on a substrate, zigzag bilayer ribbons remain magnetic for larger widths.