Regulation of saturation magnetization of magnetite by doping with group III elements

Magnetic Fe₃O₄ nanoparticles show promising applications in nanomedicine. However, the saturation magnetization (M_S) of Fe₃O₄ nanoparticles synthesized in laboratory is usually not high enough, which greatly limits their application in drug delivery and magnetic hyperthermia. Here, by accurate hybrid density functional computation, the doping behavior of group III elements (including Al, Ga, and In) and the effects on magnetic and electronic properties are well studied. The results show that the doping behavior depends on the concentration of dopants. Interestingly, appropriate Ga and In doping concentrations can significantly increase the M_S of Fe₃O₄. In addition, the doping of group III elements (Al, Ga and In) into Fe₃O₄ would not induce any defect states in the band gap but slightly increases the band gap. Our results provide a simple and feasible scheme for increasing the M_S of magnetite, which is significant for the applications of Fe₃O₄ nanoparticles in drug delivery and magnetic hyperthermia.