Magnetic properties and crystal structures of self-ordered ferromagnetic nanowires by ac electroforming

Abstract

We have investigated the magnetic properties and crystal structures of alpha-Fe and Fe21Ni79 nanowire arrays fabricated by ac electroforming into self-ordered nanosized pores in anodic aluminum oxide (AAO). The nanopores were found to have diameters of 5-100 nm and aspect ratios of 300-1000 depending on the anodization conditions. X-ray diffraction patterns provide direct experimental evidence that the alpha-Fe and Fe21Ni79 nanowires have preferred crystallographic orientations, indicating that those were electroformed in the (221) and (220) orientations, respectively. For the alpha-Fe (Fe21Ni79) nanowires, coercivity H-c and squareness M-r/M-s were found to be similar to2.02 (similar to1.20) kOe and similar to0.9 (similar to0.99), respectively. It is observed that the coercivity in Fe21Ni79 nanowires increased up to 1.35 kOe with increasing annealing temperature. (C) 2002 American Institute of Physics.