Electrical and magnetic transport properties of undoped and Ni doped ZnO thin films

• Ni doping increases conductivity of ZnO thin films.
• Mott variable range hopping mechanism dominates transport at low temperatures.
• At higher temperatures thermal activation behavior is dominant.
• Magnetoresistance follows H2 dependence at high temperature and low fields.
• Ni doped ZnO thin film shows magnetic ordering in the temperature range 5 K–300 K.

We report the transport and longitudinal magnetotransport studies of undoped and nickel (5 at.% Ni) zinc oxide thin films prepared by pulsed laser deposition technique. Low temperature (3 K) negative magnetoresistance observed in pure and Ni doped films exhibit nearly same character and is ascribed to localized magnetic moment, while at high temperatures, three times larger magnetoresistance in Ni doped ZnO has been observed and has been assigned to the magnetic scattering due to transition metal ion impurity. Enhanced magnetic ordering in NiZnO thin film up to room temperature is also observed from its magnetization data.