抄録
Ultrathin Fe3O4 films were prepared by reduction of multilayered α-Fe2O3–SiO films. The ultrathin Fe3O4 was antiferromagnetic at low temperatures, although it had a small spontaneous magnetization of 3 emu/g. The magnetization temperature curve shows a maximum at 65 K, which may corresponds to the blocking temperature of a superparamagnetism. The superparamagnetic behavior was also observed in the Mössbauer spectra. The Mössbauer spectrum at room temperature shows a paramagnetic state and is analyzed to consist of the three kinds of doublets due to Fe3+ in A site, Fe2.5+ in B site and Fe2+ in B site.
