Toshihiro Tsumori

Magnetic microstructure and noise property of electrolessly deposited CoNiFeB SoftMagnetic underlayer

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.

Electro-less CoFeNiB plating with circular anisotropy for the soft under-layer of perpendicular recording media

An anisotropic CoFeNiB soft underlayer film for use in perpendicular recording media is investigated in this paper. Electroless plating process is used to fabricate the magnetic film. Surface roughness, chemical composition and magnetic properties are obtained using AFM, X-ray fluorescence analysis and VSM, respectively. The anisotropic film indicates a circular anisotropy and a unidirectional circular flow magnetic domain pattern with a direction facilitating the magnetisation of the film.

Novel Electroless CoNiFe Soft Magnetic Underlayer on a Si Disk Substrate for Perpendicular Recording Media

A novel electroless CoNiFe soft magnetic thin film is grown on a single-crystalline Si wafer disk substrate by electrochemical deposition. The microstructure, chemical composition, magnetization, and magnetic domain structure of the films are evaluated with the use of cross-sectional transmission electron microscopy, energy-dispersive X-ray analysis, vibrating sample magnetometer and surface magneto-optical Kerr effect analysis. Results show a highly fcc oriented nanocrystalline structure which exhibits no distinct magnetic domain walls with a large in-plane unidirectional magnetic anisotropy and a low magnetic coercivity.

Reduction of grain size of Co/Pd multilayered media on Pd seeds with controlled morphology by electrochemical process

To reduce the grain size and magnetic domains of multilayered media Co/Pd on Pd seeds, the morphology of the Pd clusters was controlled by applying a pretreatment with SnCl/sub 2/ solution. Furthermore, the Pd treatment was applied to an electroless CoNiFeB soft magnetic underlayer (SUL) aiming to develop a total electrochemical preparation process of seedlayer and SUL on a disk substrate.

Effect of film thickness of electrolessly deposited CoNiFeB soft magnetic underlayer on its magnetic properties

Characteristic features of soft magnetic properties, namely, coercivity, shape of hysteresis loops and magnetic domain patterns in the CoNiFeB soft underlayer are drastically changed depending on its film thickness. Films were fabricated with an electroless deposition using DMAB (dimethylamineborane) as a reducing agent. Magnetic properties were measured with a vibrating sample magnetometer, and two-dimensional magnetic domain observations utilizing magneto-optical Kerr effect was performed with an optical surface analyzer.