Structural, morphological and magnetic characterization of electrodeposited Co–Fe–W alloys

• Small W additions (up to 9 at.%) to the Co35Fe65 binary system.
• Electrodeposited Co–Fe–W alloys characterization by XRD, SEM, TEM, Mössbauer spectroscopy and magnetic measurements.
• Production of Co–Fe–W alloys with low values of coercivity and high saturation magnetization.
• Potential materials for applications in magnetic devices such as read/write heads and hard disks.

Structural, morphological and magnetic characterization of electrodeposited Co–Fe–W alloys, containing small amounts of W (up to 9 at.%), were performed using X-ray diffractometry, scanning (SEM) and transmission (TEM) electron microscopy, Mössbauer spectroscopy and magnetization measurements. Electrodeposited (Co100−xFex)100−yWy films (x = 63–72 at.% Fe, y = 4–9 at.% W) were successfully produced varying the applied cathodic current density (ic) between 0.5 and 10 mA cm−2. X-ray diffraction results revealed a bcc-like structure for all studied compositions with average crystallite size ranging from 16 to 35 nm, as also confirmed by TEM results. SEM images indicated that needle-type morphology is dominant for the deposits containing lower W content (up to 4.5 at.%.), while a cauliflower-type behavior is observed for higher W content deposits. Room temperature Mössbauer spectra indicate the presence of two magnetic species for all samples; one component associated with an ordered Co–Fe–W fraction (crystalline grain core) and a magnetic disordered Co–Fe–W contribution, which can be attributed to the grain boundaries/grain surfaces. Magnetization was observed to be in the film plane along the film direction, except the sample prepared at ic = 10 mA cm−2 that is slightly canted from in- to out-of-plane geometry. Magnetic measurements show high saturation magnetization values accompanied by low coercivity ones for the electrodeposited Co–Fe–W alloys, making these alloys potential materials for applications in magnetic devices such as read/write heads and hard disks.