Magnetic microstructure and noise property of electrolessly deposited CoNiFeB SoftMagnetic underlayer

• Published in: IEEE transactions on magnetics Vol. 41; no. 10; pp. 3163 - 3165
• Main Authors: Sugiyama, A., Adachi, K., Sakagami, M., Yoshino, M., Kawaji, J., Asahi, T., Tsumori, T., Osaka, T.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2005; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amorphous magnetic materials; Coercive force; CoNiFe; dc noise; electroless deposition; Magnetic anisotropy; Magnetic films; Magnetic noise; Magnetic properties; Magnetism; Micromagnetics; Perpendicular magnetic anisotropy; Soft magnetic materials; soft magnetic underlayer; spike noise; striped magnetic domain; Substrates
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2005.855273

A CoNiFeB soft magnetic underlayer (SUL) was prepared by electroless deposition using dimethylamineborane as the reducing agent. A 2.5-inch NiP/Al disk was used as the substrate, on which a NiP nonmagnetic amorphous-layer was also electrolessly deposited. The coercivity H/sub c/ of as-deposited CoNiFeB films in the direction parallel to the surface exhibited a convex-parabolic dependency on the film thickness. The in-plane M-H loops and the two-dimensional Kerr effect images of the CoNiFeB film showed a nearly isotropic character with H/sub c/ of 25 Oe and no marked domain boundaries. From magnetic force microscope measurements, we confirmed that these behaviors resulted from the formation of striped magnetic domains caused by slightly perpendicular magnetic anisotropy of SUL. As far as the noise characteristics are concerned, dc noise was increased with H/sub c/, while spike noise was suppressed.