CRYSTALLOGRAPHIC ORIENTATION AND MAGNETIC ANISOTROPY IN COBALT/NOBLE METAL MULTILAYERS AND ALLOY FILMS

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Structure and magnetic anisotropy of Co/Pt and Co/Au multilayrs evaporated on (100) -oriented underlayr : (100) -oriented Pt and Au underlayrs were epitaxially grown on a (100) -oriented NaCl substrate at a substrate temperature (Ts) of 300ﾟC.Co/Pt multilayrs evaporated on a (100) -oriented Pt underlayr are of (100) -oriented fcc structure independent of Ts from 30 to 400ﾟC.Out-of-plane magnetic anisotropy is negative without substrate heating but increases with elevating substrate temperature. This suggests that the formation of Co-Pt alloy at interface enhances out-of-plane magnetic anisotropy. Next, Co/Au multilayrs were evaporated on a (100) -orinted Au underlayr at Ts=100ﾟC.We could not identify the structure through X-ray diffraction measurements.However, electron diffraction measurements revealed that (100) -orinted fcc Co and (11.0) -oriented hcp Co coexist in the Co layr. Out-of-plane magnetic anisotropy is negative irrespective of Co layr thickness. In both Co/Pt and Co/Au multilayrs was seen in-plane magnetic anisotropy with four-fold symmetry, which seems to be ascribable to the magneto-crystalline anisotropy of fcc Co and/or hcp Co.(2) Structure and magnetic anisotropy of Co-Pt and Co-Au alloy films sputtered on (100) -oriented Ag underlayr : (100) -oriented Ag underlayrs were successfully sputtered on a (100) -oriented NaCl substrate without substrate heating. Co-Pt and Co-Au alloy films were sputtered on a (100) -orinted Ag underlayr. (100) -oriented Co-Pt alloy films were epitaxially grown on a (100) -oriented Ag underlayr, provided that the Pt content was higher than 40%.On the contrary, no preferential orientation was observed in Co-Au films irrespective of the Au content. Our-of-plane magnetic anisotropy is negative irrespective of the composition in both Co-Pt and Co-Au films. In-plane magnetic anisotropy with four-fold symmetry was seen in (100) -oriented Co-Pt alloy films.