Electronic structure and magnetic order in CuxZn(1−x)O: A study GGA and GGA + U.

Abstract Based on density functional theory within GGA formalism, first-principles calculations were performed in order to study the structural, electronic, and magnetic properties of Cu-doped ZnO compound with dopant concentrations x = 0.028, 0.042, 0.056, and 0.125. It was found that Cu x Zn (1− x) O is ferromagnetic for both the closest and farthest impurity distances, but it is more stable energetically for the closest one. For all concentrations we obtained nearly half − metallic behavior. The calculations show that two substitutional Cu atoms introduce a magnetic moment of about 2.0 μ B for all dopant concentrations. The results indicate that the magnetic ground state originates from the strong hybridization between the 3 d -Cu and 2 p -O states, and suggest that the ferromagnetism could be governed by interactions between cluster spins in the CuO 4 tetrahedra. The U eff for Cu 0.042 Zn 0.958 O was calculated using the approach of Cococcioni and co-workers. The effect of Coulomb correlation U eff on the ferromagnetic stability is strongly dependent on the structure of the atomic positions and the local chemical environment. Our calculated results completely agree with experimental observations and could clarify the controversy in the literature with respect to the exchange mechanism that dominates the magnetic properties of Cu-doped ZnO. Highlights • For Cu x Zn (1− x) O, x = 0.028, 0.042, 0.056, and 0.125, the FM state is more stable than the AFM state. • Ferromagnetism in Cu-doped ZnO can be attributed to an indirect exchange mechanism of p-d hybridization. • Ferromagnetism could be governed by interactions between cluster spins in the CuO 4 tetrahedra. • The exchange mechanisms show a dependence of the position of the d states of the magnetic impurities at the Fermi level. • The effect of U eff on the ferromagnetic stability is strongly dependent on the structure of the atomic positions. [ABSTRACT FROM AUTHOR]