25th Magnetic Materials Center Seminar
October 16, 2006, 10:30
7th floor seminar room, Sengen
Microstructure of NdFeB/Ta multilayered thin film
T. Ohkubo
Thin film permanent magnets are paid attention due to the application such as magnetic recording media or microelectromechanical system (MEMS). Nd2Fe14B phase is the potential candidate because of the high magnetization and large coercivity. In order to improve the energy product, (BH)max, the perpendicular anisotropy is required to increase the remanence, and the nucleation of magnetization reversal must be suppressed to increase the coercivity. Recently, Uehara reported perpendicular anisotropic NdFeB/Ta multilayered thin film[1]. The microstructure was analyzed by TEM and EELS elemental mapping techniques. In this talk, the results will be presented, and the reason of large (BH)max will be discussed.
[1] M. Uehara, J. Magn. Magn. Mater. 284 (2004) 281-286.

Magnetic Properties and Microstructure ofTetragonally Distorted FeCo Alloys and FePt-ZrO2 Granular Films
H. Takeshita
Tetragonally distorted FeCo alloys and L10-FePt has received much attention for the high density magnetic recording media,because its magnetocrystalline anisotropy(Ku) is extremely high. Scince G.Andersson et al.[1] reported experimental results of high Ku FeCo alloys. Making FeCo alloys with tetragonally distorted structure is by epitaxial growth in conjunction with Pt in a superlattice.In this talk, I will present the relationship between Ku and FeCo thickness. ZrO2 has high melting temperature(-2550C). It would be expected to be a good matrix of FePt.In this talk, I will present the comparison magnetic properties and grain size of FePt-ZrO2 with FePt-SiO2. FePt-SiO2 was made by Seki san.

Investigation of shear band formation in bulk metallic glasses PdNiP and ZrNiAlPd
Y.Chen
Metallic glasses have many attractive properties including high strength, elastic deformability.But BMG deformation mode has not been clarified yet. Plastic flow in metallic glasses is offered by shear band. In this study, 3DAP and TEM was examined to investigate structure in shear band. Both sample were made from FIB.
In addition a single Zr65Al7.5Ni10Pd17.5 bulk metallic glass was made exhibits a large plastic strain more than 10% during the compressive deformation process. Plastic strain was much lager than 6.6% which was reported by Tohoku group. Compare with PdNiP this BMG system deformation mode is envisaged for nanoscale multistep shear bands and Tohoku group served nanocrystals around the multistep shear bands. This system is going to investigate in same technique to investigate BMG plastic deformation.