Effect of Co Seed Layers on the Magnetic Anisotropy of Au/Co Metallic Multilayers
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Effect of Co Seed Layers on the Magnetic Anisotropy of Au/Co Metallic Multilayers Masao Kamiko, Hiroyuki Mizuno, Guang-Hong Lu, Yao-Min Zhou and Ryoichi Yamamoto Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, JAPAN. ABSTRACT Au/Co(111) multilayers and a Au buffer layer were grown by MBE on Al2O3(0001) substrates using a thin Co seed layer. The influence of the Co layer on the structure of the Au/Co multilayers was studied by X-ray diffraction and reflection high-energy electron diffraction (RHEED), and compared to its effect on the magnetic anisotropy. The Au buffer layer grown on Al2O3(0001) substrates display a large fraction of (111) fiber texture, giving rise to a lack of lateral continuity in the film. The initial deposition of a few monolayers of Co onto Al2O3(0001) substrates prior to deposition of the Au buffer layer yielded (111) epitaxial films with no texture. The use of this seeded epitaxy results in a highly improved structural quality of Au/Co(111) multilayers. From the results of Low-angle X-ray diffraction and RHEED observations, we confirmed that the interfaces of Au/Co multilayers with Co seed layer are sharper than those without Co seed layer. It cleary shows that the use of Co seed layer improved the periodicity of Au/Co multilayers. The magnetic anisotropy energy of Au/Co multilayers increased by using the Co seed layer, and the high quality of structure results larger perpendicular magnetic anisotropy. INTRODUCTION In recent years the perpendicular magnetic anisotropy of metallic multilayers has been attracting much attention both from a fundamental standpoint and for applications. In several multilayers consisting of Co as a ferromagnetic element, it has been reported that the large uniaxial magnetic anisotropy with the axis perpendicular to the film plane is observed when Co layer thicknesses are smaller than several monolayers. It is known that a Au/Co multilayer system is one of the multilayer systems that exhibit marked perpendicular magnetic anisotropy[1]. Among the many combinations of film and substrate materials, much attention has been paid for the growth of metal on metal since the discoveries of fascinating properties of metallic multilayers, for example, perpendicular magnetic anisotropy and giant magneto-resistance. As has been reported in some metallic multilayers, it is well known that these properties are strongly associated with both the sharpness of interface and the quality of epitaxy. In order to achieve a better understanding of the origins of the properties of metallic multilayers, it is important to control the growth of the thin films. In order to create multilayers with both well-defined crystal and interfacial structures, we used a seeded epitaxy technique in the growth of Au/Co on single crystal Al2O3(0001) substrates by MBE. Seeded epitaxy has been expected to be a powerful method to improve P8.27.1
thin film growth in MBE deposition[2-4] and suputter deposition[5-7]. The key to seeded epitaxy is that one can stabili
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