Structure and magnetic anisotropy evolution in Au/Co/Au sandwiches upon thermal treatment

The correlation between structural and magnetic properties of Au(111)/Co(0001)/Au(111) sandwiches with perpendicular magnetic anisotropy, grown by molecular beam epitaxy, has been studied in details. Thermal treatment in the range between room temperature and 300 °C at various stages of samples growth process as well as after its completion is applied as a factor modifying the structure of studied specimens. Annealing at 150 °C does not affect substantially either crystalline structure or perpendicular magnetic anisotropy. At 250 °C the RHEED pattern of Co layers reveals the loss of the lattice coherence with Au underlayer and the analysis of synchrotron radiation reflectometry leads to the conclusion that the continuity of Co layers is lost. Structural evolution upon thermal treatment is well correlated with changes of magnetic anisotropy studied by magnetooptical Kerr effect. After annealing at 250 °C magnetization switches from out-of-plane to in-plane orientation, which is explained in terms of interfacial and magnetoelastic contributions to the sample magnetic anisotropy. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)