Control of the local magnetic states in graphene with voltage and gating

Magnetism of graphene can be created by atomic defects, either hydrogen adsorption or single-carbon vacancy formation, owing to the unpaired $\ensuremath{\pi}$ electrons around defects. Here we explore, based on rigorous first principles calculations, possibility voltage manipulation two such types magnetism in via a scanning tunneling microscope tip. We find remarkably different behavior. For hydrogen, magnetic moment switched and off with voltage-induced doping, whereas, for carbon vacancy, spin splitting bands persists, almost independent extent due coupling between $\ensuremath{\sigma}$ bonds. Furthermore, local structures near reversibly manipulated coordination mechanism an intermediate tip-defect distance moderate tip voltage, consequently leading reversal polarization bands. Voltage control states may open new avenue potential applications spintronics.