Magnetic fields parallel to electric fields were applied in the experiment to prepare cobalt thin films from the electrolyte without chemical additives. Influences of various magnetic intensities on the electrochemistry process, deposition mass and surface morphology were studied. According to the experiment, steady state current and deposition mass decreased gradually with the increase of magnetic intensities. The result of electrochemical impedance showed that transfer resistance increased with the magnetic intensity ranged from 0 to 1 T. During the electrodeposition process, cobalt near cathode is lower than other places in the solution. A gradient in the concentration of paramagnetic cobalt ions leads to a gradient in the magnetic susceptibility which would induce to a magnetic driving force when the magnetic field was applied. This magnetic driving force would push the cobalt ions away from cathode to hinder cobalt deposition resulting in decrease of steady state current and transfer resistance. The cobalt films are composed of typical nodular structures. However, hill-like structures could be observed with the increase of magnetic intensity. Cobalt grains tend to grow perpendicularly to the substrate with the condition of higher magnetic intensity due to the ferromagnetic property of cobalt atoms
