Predicted giant magnetic anisotropy energy of highly stable Ir dimer on single-vacancy graphene

We predict that a combined system of Ir dimer situated on the single-vacancy (SV) graphene is extremely stable and has high magnetic anisotropy energy (MAE), promising to be a potential candidate for high density magnetic storage. Our theoretical results show that high energy gradient in the SV graphene makes it possible to move the Ir dimer from the perfect graphene area into the center of SV (CSV), leading to the formation of the highly stable system with the Ir-Ir bond axis exactly perpendicular to the graphene plane. The calculated MAE value is as large as 25.7 meV per Ir atom. The origin of giant MAE in such a system is attributed to the difference of local densities of electronic states magnetized along different directions caused by special symmetry of Ir${}_{2}$ at CSV. We also propose a feasible avenue to assemble the Ir dimers on the graphene with the pattern of SV defects for actual applications.