| Co-Investigator(Kenkyū-buntansha) |
OHNUMA Shigehiro The Res.Ins.of Elec.& Mag.Mat.Senior Researcher, 主任研究員 (50142633)
SAWAZAKI Tatsuo Sumitomo Metal Industry Co.Researcher, 未来技術研究所, 研究員
SHIMA Toshiyuki Tohoku Univ., IMR Research Associate, 金属材料研究所, 助手 (50261508)
MITANI Seiji Tohoku Univ., IMR Research Associate, 金属材料研究所, 助手 (20250813)
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| Research Abstract |
As small sizing and high frequency use of magnetic devices are extensively required nowadays, it is an important subject in the research field of magnetic materials to fabricate magnetic thin films with high saturation magnetization and high electrical resistivity. Nanogranular thin films consisting of magnetic metal and nonmagnetic insulator have been investigated so far, and fairly good soft magnetic properties (resistivity rho=100-500 muOMEGAcm, saturation magnetization Bs-10 kG) were achieved. However, further investigation and development of soft magnetic thin films with high electrical resistivity are currently required for applications such as high density magnetic recording heads etc. In this research project, we have investigated soft magnetic properties and electrical resistivity behavior of ferromagnetic alloy/ferromagnetic insulator multi-phase granular thin films.
Granular thin film samples were prepared by a sputtering technique with composite targets of ferromagnetic alloy and ferromagnetic insulator, and microstructure, electrical resistivity and magnetic properties were examined. From a systematic investigation for many kinds of combinations of ferromagnetic alloys and ferromagnetic insulators, we found that it is important to control surface reaction of ferromagnetic insulator on the film surface. Also, we found that Fe-MgFe_2O_4 and Ni-MgFe_2O_4 systems are candidates for very good soft magnetic thin films with high saturation magnetization and high electrical resistivity. For Fe-Mg-O multi-phase granular systems, good results, such as rho=100-400 and Bs=12-16 kG,were obtained in the optimized sputtering condition.
In addition to the results mentioned above, soft magnetic thin films of Co-Fe-Al-O exhibiting very high saturation magnetization (Bs=19 kG) has been achieved although its resistivity is fairly low( rho=100 muOMEGAcm) . It is considered that the Co-Fe-Al-O film can be used for application of high density magnetic recording heads.
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