Gate voltage-dependent magnetoresistance of Zn0.8Co0.2O:H

Abstract

The magnetoresistance of a hydrogenated Zn_0.8Co_0.2O film with an inverted thin film transistor structure was measured at 7 K, in magnetic fields up to 3 T in order to verify the magnetoresistance dependency on carrier density. The gate voltage-dependent magnetoresistance was measured between −15 V and 15 V. A large positive magnetoresistance was identified at all gate biases. Changes in positive gate voltage did not result in significant changes in the magnetoresistance; however, an increase in negative gate voltage resulted in an increase in magnetoresistance and zero field resistivity. The magnetoresistance comprises a positive component, as a result of quantum conductivity correction due to the s–d exchange interaction, and a negative component induced by weak localization. The gate voltage-dependence of the positive and negative magnetoresistances was described by the density of states for ZnCoO:H.