Development of epitaxial growth technology on amorphous substrates and its application to magnetic thin films

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The aim of this research is to develop the techniques for growing epitaxial films with crystal orientation well controlled, and to apply the techniques to the fabrication of magnetic thin films. We have tried to synthesize Fe/Au superlattices that we have investigated so far, on amorphous substrates by monatomic layer control, to compare their structural and magnetic properties with those for the superlattices grown on single crystal substrates.As a preliminary experiment, we first prepared Fe(xML)/Au(xML) superlattices (1【less than or equal】x【less than or equal】5 ; ML means monatomic layer thickness) on MgO(001) single crystal substrates. We have found from the X-ray diffraction and magnetization measurements that the layer thickness is controllable with the precision of approximately 0.1 ML for our samples. Next we prepared Fe/Au superlattices on quartz glass substrates. A 100 nm thick MgO(001) underlayer was first deposited on a quartz glass by ion beam sputtering ; then Fe seed (1 … More nm) and Au buffer (50 nm) layers were deposited by UHV e-beam evaporation. Fe/Au superlattice were grown on the buffer. By using the MgO(001) underlayer first deposited, we have succeeded in the fabrication of Fe/Au superlattice with the preferred orientation (001) normal to the film plane. However, the in-plane structure is polycrystalline ; in other words, the Fe/Au superlattices have (001) texture. In the X-ray diffraction profiles, the satellite peaks corresponding to superlattice structure are definitely observed, however, the intensities are smaller than those for the monocrystalline superlattices grown on MgO single crystal substrates. This indicates that the interface roughness for the texture superlattices is larger than that for the monocrystalline superlattices. The magnitude of Fe moment and the magnetooptical Kerr spectra show no large differences between textured and monocrystalline samples, suggesting that the interface roughness gives no strong influence on these magnetic properties. On the other hand, the perpendicular magnetic anisotropies (PMA) for the textured superlattices are lower than those for monocrystalline superlattices, suggesting that the PMA is very sensitive to the interface roughness. Less