Spin-reorientation transition and magnetic phase diagrams of thin epitaxial Au(111)/Co films with W and Au overlayers

We present a study of the thickness- and temperature-driven spin-reorientation transition in thin epitaxial Au(111)/Co films grown on single-crystal sapphire Al₂O₃(1120) substrates. The transition as a function of Co film thickness was investigated in situ at T=300K by means of the magneto-optical Kerr effect at Co wedge-shaped samples prior and after coverage with W and Au overlayers. The thermal-induced transition, in particular the evolution and stability of in-plane and out-of-plane magnetization components, was studied in the temperature range from 10 to 300 K by reflectivity experiments with polarized neutrons and angular-dependent measurements with superconducting quantum interference device magnetometry. Magnetic phase diagrams, as determined by extended measurements on Au(111)/Co/Au and Au(111)/Co/W show that for the former films the perpendicular anisotropy is stable over a larger thickness region at low temperature.