Effects of Mn substitution of Co and Fe in spinel CoFe2O4 thin films

Effects of Mn substitution for Co and Fe on the structural and magnetic properties of inverse-spinel CoFe 2 O 4 have been investigated. Mn x Co 1− x Fe 2 O 4 and Mn y CoFe 2− y O 4 thin films were prepared by a sol–gel method. The observed increase of the lattice constant of Mn x Co 1− x Fe 2 O 4 indicates that Mn 2+ ions substitute the octahedral Co 2+ sites. Conversion electron Mossbauer spectroscopy data indicate that a fraction of octahedral Co 2+ ions exchange sites with tetrahedral Fe 3+ ions through Mn doping. Vibrating-sample magnetometry data exhibit a large increase of saturation magnetization for both Mn x Co 1− x Fe 2 O 4 and Mn y CoFe 2− y O 4 films compared to that of the CoFe 2 O 4 film. Such enhancement of magnetization can be explained in terms of a breaking of ferrimagnetic order induced by the Co 2+ migration.