Correlation of morphology and magnetic properties in ultrathin epitaxial Co films on Au(1 1 1)

Structural and magnetic properties of ultrathin Co films were studied by scanning tunneling microscopy and magneto-optics. Hundred nm Au(1 1 1) films grown epitaxially on mica were used as buffer layers. The initial Co nucleation at the elbows of the “herringbone” reconstruction determined the film morphology, which displayed long chains resulting from the coalescence of the self-organized Co nuclei. A height amplitude of the chains changed considerably upon film annealing. For the ex situ magnetic measurements, wedge samples were prepared, protected with a 5 nm Au layer. Using Kerr magnetometry it was possible to observe the spin reorientation transition. It turned out that the critical thickness decreases for annealed films. The magnetic surface anisotropy was determined and correlated with the film microstructure.