LAUSR

Decorating two-dimensional (2D) materials with transition-metal adatoms is an effective way to bring about new physical properties that are intriguing for applications in electronics and spintronics devices. Here, we systematically studied the coverage-dependent magnetic and electronic properties of graphene decorated by Co adatoms, based on first-principles calculations. We found that if the Co coverage is larger than 1/3[Formula: see text]ML, the Co atoms will aggregate to form a Co monolayer and then a van der Waals bilayer system between the Co monolayer and graphene forms. When the Co coverage is [Formula: see text][Formula: see text]ML, the Co adatom is spin-polarized with spin moment varying from 1.1 to 1.4[Formula: see text][Formula: see text]. The [Formula: see text] and [Formula: see text] orbitals of Co hybridize significantly with the [Formula: see text] bands of graphene, which generates a series of new bands in the energy range from [Formula: see text][Formula: see text]eV to 1[Formula: see text]eV with respect to the Dirac point of graphene. In most cases, the new bands near the Fermi level lead to topological states characterized by the quantum anomalous Hall effect.