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Detection of defect-induced magnetism in low-dimensional ZnO structures by Magnetophotocurrent

The detection of defect-induced magnetic order in single low-dimensional oxide structures is in general difficult because of the relatively small yield of magnetically ordered regions. In this work we have studied the effect of an external magnetic field on the transient photocurrent measured after light irradiation on different ZnO samples at room temperature. We found that a magnetic field produces a change in the relaxation rate of the transient photocurrent only in magnetically ordered ZnO samples. This rate can decrease or increase with field depending whether the magnetic order region is in the bulk or only at the surface of the ZnO sample. The phenomenon reported here is of importance for the development of magneto-optical low-dimensional oxides devices and provide a new guideline for the detection of magnetic order in low-dimensional magnetic semiconductors.