Preparation and Phase Separation Behavior of (Co,Fe) 3 O 4 Films

(Co,Fe) 3 O 4 films were synthesized by the sol–gel method through metalorganic compounds. The (Co,Fe) 3 O 4 films (Co:Fe = 2:1) showed the characteristic behavior of the spinodal decomposition by heat treatments within the miscibility gap. The coercive force of the spinodally decomposed films increased from 0.9 kOe for a solid solution to 2.0 kOe for films that underwent the spinodal decomposition. The nonmagnetic phase (rich in Co) formed by the spinodal decomposition contributes to the pinning of the movement of magnetic domain walls. On the other hand, the (Co,Fe) 3 O 4 films (Co:Fe = 1:1) showed the typical feature of binodal decomposition during heat treatment within the miscibility gap. The binodally decomposed films showed a slight increase in the coercive force depending upon the evolution of the magnetic region.