Detecting spin polarization of nano-crystalline manganese doped zinc oxide thin film using circular polarized light

•Highly oriented c-axis of Mn-ZnO thin film doped with nitrogen is prepared.•The optical energy gap depends on the state of circularly polarized light.•The presence of spin polarization is confirmed using simple optical method.•Magnetic measurements are consistent with the results of the optical method.

The presence of spin polarization in Mn-doped ZnO thin film is very important for spintronic applications. Spin polarization was detected using simple method. This method depends on measuring the optical transmittance using circular polarized light in visible and near infra-red region. It was found that, there is a difference in the optical energy gap of the film for circular left and circular polarized light. For temperatures > 310 K the difference in energy gap is vanished. This result is confirmed by measuring the magnetic hysteresis of the film. This work introduces a promising method for measuring the ferromagnetism in diluted magnetic semiconductors.