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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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, Mossbauer spectroscopy and magnetization measurements. Electrodeposited (Co-100 Fe-x(x))(100) W-y(y) films (x = 63-72 at.% Fe, y = 4-9 at.% W) were successfully produced varying the applied cathodic current density (i(c)) 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 M ssbauer 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 i(c) = 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. (C) 2014 Elsevier B.V. All rights reserved.