Structural and Magnetic Properties of Electrodeposited CoPt and FeCu Nanowires Embedded in Polycarbonate Membranes

CoPt and FeCu multilayered nanowires arrays were successfully electrodeposited into nanochannels of commercial track-etched polycarbonate membranes. The deposited CoPt alloy had a face centered cubic structure and displays soft magnetic properties. The magnetic measurements had detected only ferromagnetic couplings between constituent layers of Co. Magnetic Force Microscopy measurements suggest that the Co magnetic moments are perpendicular to th e wires axis and can rotate with respect to this axis in order t o minimize the interaction of demagnetizing field. Fe xCu 1-x alloys were prepared by electrochemical deposition from a sulfa te bath of iron and copper ions. The composition of the alloys was obtained by the choice of the potential applied dur ing the deposit. The obtained alloys crystallize in the fcc structure in accordance with the previous results. The first res ult obtained with FeCu nanowires denote a metastable phase for the system. The α-iron phase of stable bcc-structure at room tempera ture is ferromagnetic below its Curie temperature o f 1043 K. Above T=1193K, γ-iron phase is stable in fcc-structure. However, it can be obtained in metastable state at room temperature using the necessary metallurgic procedu res. Its magnetic properties depend on subtle eleme nts not yet clearly understood that characterize its structural propert ies. Although, the iron and the copper are normally immiscible, Eckert et al. (1993) had shown that Fe xCu 1 - x alloys of fcc-structure can be prepared by "mechan ical alloying". The obtained alloys are ferromagnetic for x values superior to 20. On the other hand, the fcc- structure alloys can also be prepared by electroche mical deposition (Uela and Kikuchi, 2004). But, in this case, no magn etic order was observed in the alloys. Therefore, t hey are paramagnetic whatever is the iron concentration.