Combined effect of strain and screw dislocation on the ferromagnetic behavior of ZnO nanowires

Abstract

Owing to its excellent structural flexibility, a noteworthy strain adaptability was discovered from the screw dislocation located in zinc oxide (ZnO) nanowires (NWs). Based on density functional theory (DFT), the electronic structure and magnetic coupling mechanism of Zn vacancies (VZn) in this dislocation while sustaining inhomogeneous strain patterns were explored. The electronic structure analysis revealed that a double screw characteristic could be observed from the center of the dislocation, where O atoms were under 3-fold coordination. This was beneficial to the capture of numerous VZn. Meanwhile, the most stable configuration was obtained under a −2% strain, which enhanced the stability and interaction of VZn, allowing the couplings of VZn to form steady VZn pairs. A stable ferromagnetic (FM) state then originated from the p-p spin couplings of surrounding O-2p orbits. It was deduced that the long-range FM ordering could be regulated by the combined effect of strain and screw dislocation.