Demagnetization of an ultrathin Co/NiO bilayer with creation of submicrometer domains controlled by temperature-induced changes of magnetic anisotropy

Abstract We have investigated the magnetization in a ferromagnetic/antiferromagnetic Co/NiO bilayer from room temperature (RT) to 200 0C. Using polar magneto-optical Kerr effect (PMOKE) based magnetometry, we observe the temperature-induced spin reorientation transition of the Co layer at 150 0C (from out-of-plane to in-plane state). Zero field cooling (ZFC) down to RT leads to the appearance of a micrometer size domain structure and demagnetization of the sample. The remanence magnetization after the ZFC process strongly depends on the temperature from which the cooling process starts (onset temperature). The domain structure and its evolution under the external out-of-plane magnetic field were studied with magnetic force and PMOKE microscopies.