Advanced Materials

Giant Coercive Field of Nanometer- Sized Iron Oxide


  • This work was supported by the Japan Science and Technology Corporation (JST), PRESTO (JST), and a Grant for the 21st Century COE Program from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. We thank Dr. Y. Song for helpful discussions, and Mr. T. Hozumi and Dr. H. Mori for help with the TEM experiments.


Nanocrystals of iron oxide in a silica matrix exhibiting a giant Hc value of 2.0 T at room temperature are reported. The nanocomposite was obtained by combining reverse-micelle and sol–gel methods. The nanocrystals of iron oxide are composed of the ϵ-Fe2O3 phase, with rod-like particles 100–140 nm long and 20–40 nm wide. The Figure shows the hysteresis curve of the nanocrystals.