Modulation effects of Cu doping on magnetic properties of Zn(Ni)O: First-principle calculations

► The electronic and magnetic properties of (Ni,Cu)-codoped ZnO are explored theoretically. ► Dopant Cu induces a long-range modulation for the Ni-Ni coupling. ► The modulation path is through the Cu-Ni magnetic interaction. ► The ferromagnetism stability is enhanced by Cu doping.