The electronic structures and magnetic properties of N-doped ZnO with and without Zn vacancy

► N-doped ZnO is a weak ferromagnet. ► Ferromagnetic stability can be increased significantly by doping the Zn vacancy (VZn). ► A Curie temperature of about 490 K can be expected in N-doped ZnO with a VZn. ► Ferromagnetism in N-doped ZnO can be attributed to hole-mediated double exchange interaction.