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成果報告書詳細
管理番号20180000000571
タイトル*平成29年度中間年報 エネルギー・環境新技術先導プログラム 磁気テープにおけるミリ波記録方式の開発研究
公開日2018/12/14
報告書年度2017 - 2017
委託先名国立大学法人東京大学 国立大学法人大阪大学 富士フイルム株式会社
プロジェクト番号P14004
部署名イノベーション推進部
和文要約
英文要約Magnetic recording media play an important role in the recent big data/IoT society. In order to improve the recording density, down-sizing the particle size of the magnetic recording material is necessary. Epsilon iron oxide draws much attention due to the largest coercive field value at room temperature among ferrite magnets and electromagnetic wave absorption property. Furthermore, epsilon iron oxide can maintain its ferromagnetic properties down to single nanometer size of 8 nm. In this project, our objective is to experimentally demonstrate a new recording system of magnetization reversal by combining external magnetic field and electromagnetic wave irradiation using epsilon iron oxide.
First, statistical thermodynamic calculations were performed to investigate the electromagnetic wave intensity required for magnetization reversal. Based on the results of the calculation, metal-substituted epsilon iron oxide magnetic powder was synthesized. Magnetic films were also prepared by synthesizing a dispersed solution of metal-substituted epsilon iron oxide. Additionally, an electromagnetic wave generation system was constructed using a high-intensity femtosecond laser. By conducting electromagnetic field analysis, we theoretically calculated a focusing device to enhance the incident electromagnetic wave. Furthermore, towards the observation of the magnetization reversal assisted by electromagnetic waves, we investigated the film preparation process. Rhodium-substituted epsilon iron oxide nanoparticles were dispersed in an organic solvent with urethane resin and vinyl chloride resin, and the resulting solution was dropped on a film. By drying under a magnetic field, crystallographically highly oriented magnetic film was prepared. The obtained film showed a coercive field of 35 kOe, which is the largest value among ferrite magnets. Furthermore, the film exhibited an even large value of 45 kOe at -73 °C. Using the same film preparation technique, a crystallographically oriented film of gallium-substituted epsilon iron oxide was prepared, and rectangular shape magnetic hysteresis loop was observed. Using these film samples, we are performing irradiation experiment under the static magnetic field for magnetization reversal.
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