Prediction of quantum anomalous Hall effect and giant magnetic anisotropy in graphene with adsorbed Ir-based dimers

Abstract

In order to explore the quantum anomalous Hall effect in two-dimensional materials, it is crucial to find membrane systems with a robust out-of-plane magnetization. By adsorbing certain transition metal dimers onto graphene, a robust Chern insulator with giant magnetic anisotropy can be realized in this Dirac electronic material. We have investigated the structural, magnetic, and topological properties of graphene with adsorbed Ir-based dimers by density-functional calculations as well as the tight-binding model. Our results reveal that two adsorption systems, Ir-Fe@G and Ir2@BG, possess a giant magnetic anisotropy of 31.5 and 130.1 meV, respectively, as well as nontrivial topological bandgaps of 30.4 and 11.2 meV at the Fermi level. Integer anomalous Hall conductivities of ±2e2/h emerge as the chemical potential scans through the bandgaps. The adsorption dimers are perpendicular to the graphene layer and robust against thermal fluctuation. Both the magnetic anisotropy and the topological bandgaps can be effectively modulated by the electric field, which makes them feasible in the application of quantum devices.