Switching behaviour of single nanowires inside dense nickel nanowire arrays

Summary form only given. The suitability of nickel nanowire arrays for perpendicular magnetic storage media with areal densities beyond the superparamagnetic limit (>70 Gbit/in/sup 2/) is analyzed in this paper. Highly ordered alumina pore channel arrays are used as templates for the fabrication of magnetic nanowire arrays with a periodicity of 65 (180 Gbit/in/sup 2/) and 100 nm (75 Gbit/in/sup 2/) and pore diameters between 30 and 55 nm. A nearly perfect hexagonal arrangement for the magnetic columns occurs only inside very narrow process windows for periodic distances of 65, 100 and 500 nm, and - in contrast to most publications in this field - a degree of pore filling of almost 100% was achieved. Here, we will focus on nickel as a filling material due to its negligible magneto-crystalline anisotropy, so that the interactions between the anisotropy resulting from the nanowire shape and the stray field inside the magnetic arrays can be studied in detail. The small magnetic moment and the large exchange lengths (/spl lambda//sub ex/= (A/2K/sub 1/)/sup 05/ /spl ap/ 20 nm) of nickel leads to low dipole interactions between nanowires and a huge anisotropy along the column axis which enables nickel as a suitable material for pattern perpendicular magnetic media.