Study of ultrathin magnetic cobalt films on MgO(001)

In-situ magneto-optical Kerr effect measurements have been done to study the evolution of the magnetic properties of ultrathin cobalt films on MgO(001) surface. A magnetic dead layer is found to exist at the MgO/Co interface, thickness of which is influenced by possible surface contamination of MgO substrate. X-ray photoelectron spectroscopy measurements show that etching the substrate with 500 eV Ar ions results in partial removal of carbon contamination. A lower carbon contamination results in reduction of the thickness of dead layer from 2.2 nm to 1.3 nm. At thicknesses below 3 nm, Co islands exhibit superparamagnetic relaxation. For higher film thickness, a well-defined uniaxial magnetic anisotropy develops along (100) direction. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739271]