First-principles study on the coexistence of different valence states of Zn vacancy, Cu1+/2+ doping, and Hi in ZnO magnetic switch

In this study, we used first principles to investigate the magnetic sources and switches of Zn34Cu1+HiO36(V-Zn(0)), Zn34Cu1+HiO36(V-Zn(2-)), Zn34Cu2+HiO36(V-Zn(0)), and Zn34Cu2+HiO36(V-Zn(2-)) systems. On the basis of formation energy, phonon spectrum, and temporal variation of energy, we concluded that the above systems were all in a stable state. The doped system can be magnetized by adjusting the valence state of Zn vacancy, and the Zn34Cu1+HiO36(V-Zn(0)) and Zn34Cu2+HiO36(V-Zn(2-)) systems demonstrated magnetism. We found that the Zn34Cu1+HiO36(V(Zn)0) system acquired magnetism through (O-(sic)(center dot) + V-Zn '')(x) double left right arrow (up arrow O-center dot + V-Zn '' + up arrow O-center dot)(x) double left right arrow (up arrow O-center dot + V-Zn '' + down arrow O-center dot)(x) super- and double-exchange interactions, whereas the magnetism of the Zn(34)Cu(2+)HiO(36)(V-Zn(2-)) system originated mainly from the action of the O-1 -V-Zn(2-)-Cu2+-bound magnetic polaron and double exchange. Our theory provides a new approach for the use of magnetic switches in magnetic semiconductors.