Magnetic behavior of arrays of nickel nanowires: Effect of microstructure and aspect ratio

Arrays of nickel nanowires with aspect ratio of ∼1200 and diameters ranging between 25 and 100 nm have been fabricated by electrodeposition in etched ion track templates. Samples with different areal densities ranging from 1 × 106 cm−2 to 1 × 108 cm−2 have been prepared for this study. Magnetic measurements were performed at room temperature for different aspect ratios and diameters of the wires. Coercivity of the wires showed a strong dependence on aspect ratio (l/d), diameter and microstructure. In the case of parallel applied field coercivity of the wires has maximum value at ∼40 nm diameter. The wires with high areal densities showed relatively lower coercivities as compared to the low density samples. The results have been discussed by taking into account various magnetic anisotropies originating from the shape and crystalline nature of the wires, and the magnetostatic interactions among the wires.

► Arrays of nickel nanowires with varying aspect ratio and diameter ranging between 25 and 100 nm have been synthesized by electrodeposition in polycarbonate templates.
► Magnetic measurements at room temperature showed that easy axes of magnetization lie parallel to the wire-long axis with enhanced coercivity in that direction.
► Analyses were performed to study the effect of microstructure and aspect ratio on the magnetic properties of Ni nanowires.
► Coercivity versus aspect ratio showed an influence of the length that gets stronger with areal density of nanowires.