Roughness and Magnetic Properties of Pt/Co Multilayered Films
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ROUGHNESS AND MAGNETIC PROPERTIES OF Pt/Co MULTILAYERED FILMS S.Sumi, Y.Kusumoto, Y.Teragaki and K.Torazawa Sanyo Electric Co.,Ltd., Anpachi-cho, Gifu 503-01, Japan S.Tsunashima and S.Uchiyama Dept. of Electronics, Nagoya University, Nagoya 464-01, Japan
ABSTRACT Magnetic properties and roughness of sputter-deposited Pt/Co films power, strongly depend on preparation conditions such as rf-input underlayers and their etching. Large coercivity was obtained by using suitable underlayers such as ZnO and adjusting input power higher for Co and lower for Pt. The coercivity in Pt/Co films seems to depend on the roughness of the surface and/or the layer interface as well as the perpendicular anisotropy.
INTRODUCTION The relationship between the magnetic properties and the structure is always a very attractive problem in magnetic thin films. In particular, multilayered films such as Pt/Co will present a new idea since they consist of columnar crystallites with multilayered structure which is essential to the perpendicular magnetic anisotropy [1][2]. Therefore, the magnetic properties of the multilayered films have been considered to be much influenced by the surface roughness and the film morphology [3][4][5]. It is well known that Pt/Co films with large perpendicular magnetic anisotropy and enhanced Kerr effect at the shorter wavelength [6] are one of the promising materials for a high density magneto-optical recording medium. However, since lower media noise as well as higher stability of the recorded domains are required for such materials, it is still important for Pt/Co films to achieve both higher coercivity and better surface flatness [7]. Since the (111) orientation as well as the layer interface are important for the perpendicular anisotropy of Pt/Co films [8], it is of much interest to investigate the relationship between the structures and the magnetic properties. We have already reported that the sputter etching of SiN underlayers flatten the film surface [9] and that the hcp(002) orientation of ZnO underlayers enhance the fcc(11) orientation of Pt/Co films [10]. It was also reported that in the reactive sputtering of ZnO with Ar+0 2 gas and a ZnO target, the crystal orientation depended on the 02 pressure[11]. According to these facts, we further tried to control the structures of Pt/Co films, namely, the roughness of the film surface and interface and the crystal the etching of orientation, by adjusting preparation parameters in underlayers, the reactive sputtering of ZnO underlayers and the sputtering of Pt/Co films. In this paper, we report that the magnetic and structural properties of the Pt/Co sputtered films strongly depend on the properties of underlayers and on the input powers for Pt and Co targets, and discuss the relationship between the structure and the magnetic properties of the films.
Mat. Res. Soc. Symp. Proc. Vol. 313. c1993 Materials Research Society
526
EXPERIMENTAL PROCEDURE Pt/Co films consisting of (17A Pt/5A Co)x9 bilayers were prepared by rf magnetron sputtering onto glass substrat
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