Manipulation of Electronic and Magnetic Properties of 3d Transition Metal (Cr, Mn, Fe) Hexamers on Graphene with Vacancy Defects: Insights from First-Principles Theory

One of the possible ways to introduce magnetism in graphene is to trap highly mobile transition metal atoms at defect sites in graphene. In this paper, based on Born–Oppenheimer molecular dynamics simulations, we investigated the self-assembly of transition metal hexamers X₆ (X = Cr, Mn, and Fe) on graphene with mono/divacancy defects and studied the fundamental electronic and magnetic properties of the resulting X₆ clusters on graphene. Interestingly, the ground state Cr₆ and Fe₆ hexamers on divacancy defects in graphene show quite small energy differences between in-plane and out-of-plane magnetism. By applying external electric fields, the easy axis of magnetization can be switched between in-plane and out-of-plane, which demonstrates potential applications in electric field-assisted magnetic recording and quantum computing.