The effect of thermal annealing on the magnetic properties of graphene oxide quantum dots.

• The effect of thermal annealing on the magnetic properties of GOQDs was clarified. • All the annealed GOQDs samples show paramagnetism. • The magnetic moment and the magnetic density vary with the annealing temperature. • The main magnetic source of the annealed GOQDs change with the annealing temperature. The magnetism of graphene oxide quantum dots (GOQDs) has attracted much attention for the prospective applications in spintronics, which is relevant to the oxidation degree. Although the oxidation degree of GOQDs can be tuned by altering the annealing temperature, the specific effect of thermal annealing on the magnetic properties of GOQDs have not been identified. In this study, we report the effect of thermal annealing on the magnetic properties of GOQDs. All the annealed GOQDs samples show paramagnetism. Hydroxyl groups and vacancies on the basal-plane, and the phenolic hydroxyl passivated zigzag edges give various contribution to the magnetism determined by the annealing temperature. Our studies clarified the effect of thermal annealing on the magnetic properties of GOQDs, that would give benefits to their prospective applications in spintronics. [ABSTRACT FROM AUTHOR]