Pulsed Electrodeposition of Nanocrystalline CoNiFe Soft Magnetic Thin Films

A pulsed electrodeposition method was applied to the preparation of soft magnetic CoNiFe films in the compositional region corresponding to the phase boundary between face-centered cubic (fcc) and body-centered cubic (bcc) structures. Crystalline grain size was found to be almost the same, smaller than 10 nm, and independent of the duty cycle which is the ratio of the pulse-on time to the pulse-on plus pulse-off period. Depending on the operating conditions, the ratio of bcc to fcc varied. Current efficiency decreased with decreasing duty cycle and pulse current density. The intensity ratio of bcc(110) to fcc(111) X-ray diffraction peaks showed a maximum at the operating conditions in which the transition from kinetic to mass-transfer controlled deposition occurred with only a slight increase of Fe content (approximately 1 atom %). Magnetic properties were suggested to be controllable by adjusting the bcc-fcc ratio using pulsed electrodeposition.