Origin of Magnetism from Native Point Defects in ZnO

Based on the first-principle calculations by using the Korringa?CKohn?CRostoker coherent potential approximation (KKR-CPA) method in connection with the local density approximation (LDA), we study theoretically the electronic and magnetic properties of different point defects in ZnO, which are Zinc interstitials (Zn_i), Zinc antisites (Zn_O), Oxygen interstitials (O_i) and Oxygen antisites (O_Zn) defects in ZnO. The supercell calculations were also performed using the full potential local-orbital (FPLO) band structure scheme. This work presents detailed information about total and local density of states at some concentrations of these defects; the stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing calculating their total energy. The results show on one hand that Zn_i and Zn_O produce a shallow donor bellow the bottom of the conduction band (CB), while O_i and O_Zn produces the shallow acceptors above the top of the valence band (VB), and moment magnetic; on other hand that the ferromagnetic state is more stable than the spin-glass in Oxygen interstitials (O_i) and vice versa for oxygen antisites (O_Zn) of native point defects in ZnO. The other native point defects (Zn_i, Zn_O, V_O, and V_Zn) have a zero magnetic moment. The results show that the Curie temperature increases with the concentration of interstitial oxygen.