A CASTEP study on magnetic properties of C-doped ZnO crystal

The CASTEP calculations based on the density function theory (DFT) have been carried out in studying magnetic properties of C-doped ZnO crystal. The long-range ferromagnetism (FM) can be attributed to coupling between C energy levels. We also investigate effects of oxygen vacancies and nitrogen impurities on FM properties. It is obvious that oxygen vacancies are unfavorable to stabilize the FM. However, nitrogen impurities can enhance FM coupling, which indicates that hole-carriers play a crucial role in the observed FM behavior. In addition, we also analyze strain effect on FM of C-doped ZnO.