Tuning magnetoresistance and exchange coupling in ZnO by doping transition metals

A systematic study focused on the magneto-transport properties of transition metal (Cu or Co) doped ZnO thin films is performed to elucidate the role of doping on tuning the band structure and exchange coupling in wide band gap oxides. Detailed theoretical fittings suggest that the negative magnetoresistance (MR) originates from the spin-dependent scattering due to the high-order sp-d exchange interaction, while the positive MR can be well described by a model invoking two spin split subbands. Our results suggest that with different dopants both the electronic band structure and the exchange coupling in ZnO can be rationally tailored.