Template synthesis of NiFe nanowires using diblock copolymers

Fabrication of self-assembled diblock copolymer nanoporous templates, electrodeposition of NiFe nanowires into the templates, and their magnetic behaviour were studied. Standard spin coated polymer films on gold coated substrates were subjected to usual field annealing and etching procedures for successful removal of one of the polymer blocks and to obtain hexagonally ordered nanoporous templates. Electrodeposition of NiFe nanowires into these template pores was carried out in potentiostatic three-electrode configuration for different deposition times while keeping the deposition parameters such as electrolyte pH value and the reduction potential constant at 3.82 and −1.0 V, respectively. Current–time profiles obtained during the deposition process were analyzed to understand the mechanism of growth. Using the SEM image of the nanoporous template, the pore-diameter, inter-pore distance and pore-length were estimated as 35, 100 and 700 nm, respectively. Hysteresis loops of the nanowires exhibit easy axis of magnetization along the wire axis. The magnetic behaviour was analyzed taking into account the wire dimensions and the respective contributions from dipolar interactions and demagnetizing energy.