Ferromagnetism in carbon-doped ZnO films from first-principle study

First-principle calculations based on density functional theory have been performed on the nonmagnetic 2p   light element C-doped ZnO thin films. The total energies and magnetism of the system are calculated with a ten-layer slab along (101¯0) direction. The results show that the C-doped ZnO thin films are ferromagnetic. A single C is preferable to occupy the subsurface site. As the concentration of C atoms increases, the ferromagnetic coupling among the dopants is more favorable, and they tend to form a cluster around the Zn atom at the film surface. The ferromagnetism is predicted to be mainly from a p–dp–d exchange-like p–pp–p coupling interaction and a p–dp–d exchange hybridization. The p–pp–p coupling interaction is the dominative mechanism.