Seeded epitaxy of Co/Au(1 1 1) multilayers on α-Al2O3(0 0 0 1): Influence of Co seed layer

The influence of a Co seed layer on the structural and magnetic properties of Co/Au(1 1 1) multilayers grown onto α-Al2O3(0 0 0 1) single crystal substrates by molecular beam epitaxy has been studied by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), and vibrating a sample magnetometer (VSM). The initial deposition of the Co seed layer onto Al2O3(0 0 0 1) prior to the deposition of an Au buffer layer yielded high-quality fcc-Au(1 1 1) oriented epitaxial films and a well-known (23 × 1) surface reconstruction structure. The RHEED results proved that the Co seed layer enhanced the layer-by-layer growth of the Co/Au multilayer on Au(1 1 1). The Co seed layer also improved the crystalline quality of the consequent Co/Au(1 1 1) multilayer. The results of XRD revealed that interfaces of the Co/Au multilayers with the Co seed layer were sharper than those without a seed layer. The magnetic anisotropy energy of the Co/Au multilayers was increased by using the Co seed layer. This indicated that a high structural quality resulted in a greater perpendicular magnetic anisotropy. However, this structural control was the result of the decrease in the coercive force and remanent magnetization.