Magnetotransport in Co-doped ZnO nanowires.

Electrical and magnetotransport measurements were performed on individual Co-doped ZnO dilute magnetic semiconductor nanowires. The electron transport studies show that the electron mobility could be as high as 75 cm(2)/(V.s), and we observed positive magnetoresistivity (MR) at low magnetic field and negative MR at higher magnetic field. s-d exchange-induced spin splitting of the conduction band could account for positive MR while suppression of weak localization of impurity centers could account for the negative MR. Lowering the carrier concentration in these nanowires through the application of a gate voltage tends to induce a larger magnitude MR as well as additional fine structure in the MR curves.