LAUSR

Abstract Based on density functional theory within GGA and GGA+U formalisms, first-principles spin-polarized calculations have been performed to study the ferromagnetic orderings in Co x Cu 0.042 Zn 1−( x +0.042) O ( x  = 0 and 0.042). The effect of impurity distances on ferromagnetic and antiferromagnetic ground state in Cu 0.042 Zn 0.958 O with GGA scheme has been studied, and compared with the available experimental and theoretical data. Results show that Cu 0.042 Zn 0.958 O is ferromagnetic for both the closest and farthest impurity distances, but it is more stable for the closest one. The system is nearly half metallic and room temperature ferromagnetism is expected. When two Zn 2+ ions are replaced by two Co 2+ ions in Cu 0.042 Zn 0.958 O with GGA and GGA+U formalisms, both the local magnetic moment in 3 d -Cu and energy difference are reduced. This is in good agreement with the experimental observations, where the room temperature ferromagnetism in Cu 0.04 Zn 0.96 O is suppressed when it is doped with Co (4%). When the U parameter for 3 d -Cu is considered, the ground state for Cu 0.042 Zn 0.958 O system remains ferromagnetic. On the other hand, the ferromagnetic ground state found for Co 0.042 Cu 0.042 Zn 0.916 O changes to antiferromagnetic with both GGA and GGA+U schemes. Results with GGA and GGA+U also display a distortion around the impurity-O 4 tetrahedron, enhanced antiferromagnetic interaction between Cu Cu ion and their surrounding atoms, and charge transfer from Co(3 d ) to Cu(3 d ) via O(2 p ) atoms by substitution of Zn 2+ by Co 2+ in Cu-doped ZnO. As a result, both the local magnetic moment in 3 d -Cu and energy difference of Co x Cu 0.042 Zn 1−( x +0.042) O system are reduced.