SiO_2ナノリアクター法により合成されたL1_0-FePtナノ微粒子の構造および磁気特性の詳細な評価

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This paper describes detailed studies on structural and magnetic properties of L1_0-FePt nanoparticles synthesized via the recently developed "SiO_2-nanoreactor" method (Appl. Phys. Lett.87 032503 (2005)). Monodisperse and magnetically superior L1_0-FePt nanoparticles can be prepared by annealing at 900℃. Thus-obtained L1_0-FePt nanocrystals can be made dispersible in not only water but also common organic solvents, e.g., toluene, chloroform and hexane, while keeping their superior magnetic properties. The hysteresis loop of the L1_0-FePt nanoparticles dispersed in solvents showed superparamagnetic-like behavior at room temperature due to the free motions of nanoparticles. Analyses of the hysteresis loop by Langevin function suggest that the easy axis of the solvent-dispersed nanoparticles can be aligned by the external magnetic field of about 10 kOe. The hysteresis loop of the water-dispersed nanocrystals, which were frozen under an external field of 50 kOe, was almost rectangular indicating that their magnetic and structural orientation could be attained.
社団法人日本磁気学会の論文
2006-07-01