High coercivity in SiO[sub 2]-doped CoFe[sub 2]O[sub 4] powders and thin films.

Mo¨ssbauer and magnetic studies have shown that 1-2 wt % of SiO[sub 2] could be dissolved in the CoFe[sub 2]O[sub 4] structure. Changes in magnetization and Curie temperature were observed. The presence of SiO[sub 2] might enhance magnetic anisotropy. Coercivity values of up to 3.5 kOe were measured for mechanically alloyed CoFe[sub 2]O[sub 4]/SiO[sub 2] powders. High coercivities were also achieved in SiO[sub 2]-doped Co-ferrite thin films prepared by sputtering technique. The Co-ferrite thin film deposited on a silicon wafer using a 5 wt % SiO[sub 2]/Co-ferrite target possessed a coercivity of 7.4 kOe. Spring-magnet behavior was observed, indicating the possible presence of remanence enhancement due to exchange coupling because of nanocrystalline structure. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]