Tailoring the Morphology, Structure and Magnetic Properties of Electrodeposited CoFe Films onto Si(100) by In-Situ Uniform and Gradient High Magnetic Fields

In this work uniform high magnetic field of up to 12 tesla and well-defined magnetic field gradients were in-situ applied during the electrodeposition process of CoFe alloy films on Si(100) substrate with Ni seed-layer. The evolution of morphology obtained by LSCM and AFM revealed that the electrodeposition under uniform or gradient magnetic fields provides advantage of forming high quality films with small grains size and low surface roughness. The X-ray diffraction measurements revealed that the crystalline structure of the films changed with the increase of magnetic flux density from face-centered cubic (fcc) at 0 T to body-centered cubic (bcc) at 12 T. However, the formation of a mixture phase (fcc+bcc) under gradient magnetic fields reflected a negative effect of the field gradient force on the transformation from fcc phase to bcc phase. With increasing magnetic flux density (B), the saturation magnetization (Ms) and coercive force (Hc) of the films increased, while in the case of B = 12 T, both of Ms and Hc decreased. It could be ascribed to the changes in the chemical composition and the formation of the mixture phases, due to the combined effects of the paramagnetic force, micro-MHD and the field gradient force under different magnetic field conditions.