N-doped ZnO thin films and nanowires: energetics, impurity distribution and magnetism

Abstract

Calculations based on density functional theory with generalized gradient approximation for exchange and correlation potential show that N-doped ZnO thin films and nanowires are magnetic. In neutral state, a total moment of 1 μB per N atom is introduced with 0.3–0.6 μB from N 2p orbitals. The mechanism contributing to magnetism in N-doped ZnO systems, however, is different from that in conventional transition metal-doped ZnO. Here magnetism is due to the holes in N 2p states induced by the substitution of oxygen with nitrogen. The N atoms show no tendency for clustering either on the ZnO thin film surfaces or on the NW surfaces, but they prefer the surface sites over the bulk sites. This study provides physical insight into the origin of magnetism in the new magnetic materials with no magnetic elements.