  Continuous miniaturization of magnetic units in spintronics and quantum
computing devices inspires efforts to search for magnetic nanostructures with
large magnetic anisotropy energy (MAE). Typical nanostructures including
molecular magnets, magnetic nanoclusters and magnetic nanowires have MAEs of a
few meV so their blocking temperature is mostly lower than 50 K. In this work,
we demonstrated the feasibility of achieving giant MAE in systems with
transition metal dimers on defected and decorated graphene, based on density
functional theory calculations. In particular, either a Pt-Ir dimer on a single
vacancy or an Os-Ru dimer on a nitrogen-decorated divacancy possesses an MAE
larger than 60 meV and high structural stability. Interestingly, their magnetic
anisotropy can be conveniently manipulated by using external electric field.
These features make them good candidates for the use in room temperature
spintronics and quantum computing devices.
