Magnetic characterization of nickel-rich NiFe nanowires grown by pulsed electrodeposition

Nickel-rich NiFe nanowires with well-controlled diameters and compositions are fabricated in various porous alumina templates by using a pulsed electrochemical deposition technique. The average pore diameter of the templates is tuned either by coating the pore walls with thin silica layers using an atomic layer deposition (ALD) technique or by applying a chemical pore widening process. The composition of the alloy is controlled by varying the frequency of the deposition pulse. The coercivity of the nanowire array is influenced by its texture and the amount of iron content in the alloy. The effective field and the saturation magnetization are found to be reinforced with the decrease in Ni content. A distinct enhancement of the axial coercivity and squareness of permalloy, Ni80Fe20, nanowire array are obtained by decreasing the average nanowire diameter. The processes of magnetization reversal in Ni80Fe20 nanowire array are investigated. The temperature dependence of Ni80Fe20 nanowires coercivity is interpreted in accordance with magnetization fluctuation over a single energy barrier.