Spin polarization in Zn0.95 Co0.05O:(Al,Cu) thin films

ZnCoO : Al, ZnCoO : (Al,Cu), and reference samples without Co have been grown by pulsed laser deposition to investigate the influence of Co-dopants and Cu-codopants on the magneto transport properties of ZnO. Positive magnetoresistance and anomalous Hall effect have been observed for ZnCoO : (Al,Cu). Versatile theoretical approaches for modelling positive magnetoresistance in ZnO-based diluted magnetic semiconductors are still to be developed. Negative magnetoresistance due to the scattering of spin-polarized charge carriers at isolated magnetic impurities has been observed in ZnO : (Al,Cu) without Co-dopants and successfully modelled. Cu-codopants enhance the positive and negative magnetoresistance in ZnCoO :Al and ZnO : Al, respectively, by one order of magnitude.