Tunable Magnetic State in AA-Stacked Bilayer Zigzag Graphene Nanoribbon by Increasing Thickness

The density functional theory was utilized to investigate the likelihood of a tunable magnetic state in the AA-stacked bilayer zigzag graphene nanoribbon. The non-magnetic ground states at certain thicknesses were found, but then the magnetic ground states at the other thicknesses were observed. This happens by increasing the thickness so that the van der Waals force becomes weak. This creates spin polarization as the bonding between layers can be overcome. The phase transitions of magnetic ground states were also observed at a large thickness as applying the doping. This signified that the new magnetic ground state is still tunable by applying dope.