Distribution of magnetic moments in Co/Pt and Co/Pt/Ir/Pt multilayers detected by magnetic x-ray absorption

Abstract

Circular magnetic x-ray dichroism (CMXD) was observed at the Pt and Ir L2,3 edges in the multilayered structures 25·(4 Å Co+30 Å Pt) and 25·(4 Å Co+11 Å Pt+8 Å Ir+11 Å Pt). The samples were prepared by sputtering and show a large perpendicular anisotropy. The magnetic absorption at the Pt and Ir L2,3 edges was measured in an external magnetic field of 0.15 T perpendicular to the surface. The results indicate a significant spin polarization of the Pt and Ir layers. By comparison with the corresponding CMXD signals of Pt and Ir impurities in a ferromagnetic iron host we estimated the local spin and orbital moments. The results show that the innermost three monolayers in both systems couple ferromagnetically to the Co layers with an average magnetic moment of about 0.01 μB.