Spin reorientation transition of antiferromagnetic NiO/CoO/MgO(001) and its effect on the Py magnetic anisotropy in Py/NiO/CoO/MgO(001)

The effect of antiferromagnetic (AFM) layer on the magnetic properties of ferromagnetic (FM) layer in FM/AFM systems highly depends on the AFM spin configurations. Comparing to the many available tools for FM measurement, there is limited experimental techniques for the AFM spin measurement, thus limiting the fundamental understanding of why and how the AFM spins induce a magnetic anisotropy in the FM layer. Using x-ray magnetic linear dichroism (XMLD) measurement, we determined the AFM spin orientation in epitaxial NiO/CoO/MgO(001) system at room temperature. We find that the NiO AFM spins undergo a spin reorientation transition (SRT) from out-of-plane to in-plane direction as a function of CoO or NiO thickness. We constructed a complete phase diagram of the NiO spin orientation in the NiO and CoO thickness plane. Then utilizing Magneto-Optic Kerr Effect combined with a rotation magnetic field (ROTMOKE), we investigated the Py magnetic anisotropy in Py/NiO/CoO/MgO(001) system. We find that different NiO spin orientations have very different effects on the induced magnetic anisotropy of the Py film.