Effect of Superparamagnetic Fe<sub>3</sub>O<sub>4</sub> Nanoparticles on Schottky Barriers of Graphene

We demonstrated the effect of superparamagnetic Fe ₃ O ₄ nanoparticles on the Schottky barriers of graphene, in which the Fe ₃ O ₄ nanoparticles were fabricated by a hydrothermal method, and the single-layer graphene sheets were mechanically exfoliated from Kish graphite. The Fe ₃ O ₄ nanoparticles were superparamagnetic with the saturation magnetic moment of ~32emu/g at room temperature. We have found that the Fe ₃ O ₄ nanoparticles decorated on the graphene surface can dramatically modify the Schottky barriers of the whole devices possibly due to the magnetic stray field from the Fe ₃ O ₄ nanoparticles in proximity to graphene. The Schottky barrier could be further tuned by the quantity of Fe ₃ O ₄ nanoparticles.