Effect of aspect ratio on the magnetic properties of nickel nanowires

Abstract

Nickel nanowires with a diameter of ∼200 nm were prepared using the electrodeposition technique. The length of the nanowires was varied from 0.7 to 5.6 μm, which corresponds to the change in the aspect ratio from 3.5 to 28. Field emission scanning electron microscopy and x-ray diffraction spectra confirm the formation of nickel nanowires. In-plane and out-of-plane coercivity and remanence of the samples determined from direct current magnetic hysteresis loops suggest the magnetic easy axis of the nanowires along their transverse direction. As a result, magnetic hardness along the axis of the nanowires is higher than that perpendicular to it. The temperature dependence (80 K≤T≤350 K) of coercivity and squareness ratio of the samples has also been studied in detail. The vortex configuration of magnetization in the individual nanowires along with magnetostatic interaction among them has been suggested as the possible explanation for the observed magnetic properties of these nanowires in the present study.