The electrical transport behavior of Zn-treated Zn_1-xMn_xO bulks

Zn_1-xMn_xO bulks have been prepared by the solid state reaction method. Zn vapor treatment has been carried out to adjust the carrier concentration. For the Zn treated Zn_1-xMn_xO bulks, analysis of the temperature dependence of resistance and the field dependence of magnetoresistance demonstrates that the bound magnetic polarons (BMPs) play an important role in the electrical transport behavior. The hopping of BMPs dominates the electrical conduction behavior when temperature is below 170 K. At low temperature, paramagnetic Zn_1-xMn_xO bulks show a large magnetoresistance effect, which indicates that the large magnetoresistance effect in transition-metal doped ZnO dilute magnetic semiconductors is independent of their magnetic states.