Effect of magnetic field on the electrodeposition of Fe, Co into the poresof anodic film on aluminum

Ferromagnetic Fe or Co was electrodeposited into the pores in aluminum anod ic oxide film to produce a magnetic anodic film, and the effects of magneti c field during electrodeposition on the deposition characteristics of the m etals and coercivity of the produced anodic film were investigated. Fe was electrodeposited into the pores in anodic film using a mixed solution (pH=3 .8) of FeSO4(NH4)SO4. 6H(2)O (0.20 mol/l) and H3BO4 (0.48 mol/l) at 20 degr ees C with constant applied voltage of 10 V, and Co using a mixed solution (pH=4.5) of CoSO4,7H(2)O (0.10 mol/l) and H3BO4 (0.48 mol/l). It has been f ound that for the Fe-deposited anodic film the coercivity increased with in creasing length of deposited Fe particles and decreased with increasing dia meter (or porosity). The application of magnetic field during electrodeposi tion of Fe had little influence on the coercivity of the anodic film. For t he Co-deposited anodic film the coercivity increased with increasing length of deposited Fe particles and increased unexpectedly with increasing diame ter. The perpendicular coercivity of the Co-deposited anodic film was signi ficantly increased by the application of magnetic field during the electrod eposition. The unexpected coercivity increase with diameter and the increas e of the perpendicular coercivity of Co-deposited film by the application o f magnetic field were closely related to the preferred orientation of Co cr ystals in the anodic film. (C) 2000 American Institute of Physics. [S0021- 8979(00)34108-1].