Tailoring of Magnetic Easy Axis of Nickel Nanowires by Varying Diameter

Anodized aluminum oxide (AAO) templates with an average diameter of D1∼20nm and D2∼200nm are synthesized by two-step anodization. Nickel nanowires are fabricated by AC electro deposition with less microstructure defects at low voltage in AAO templates. Magnetic properties of compact nickel (Ni) nanowires show that easy axis is parallel to nanowire axis for diameter D1∼20nm while by varying diameter from D1∼20nm to D2∼200nm, easy axis shifts to perpendicular direction of nanowire axis. This shifting of magnetic easy axis from parallel to perpendicular direction is mainly due to shape anisotropy and interactive fields between the wires. The competition between shape anisotropy (due to individual wire) and interactive fields by varying diameter of nanowires could result in tailoring of the direction of magnetic easy axis of nanowires.