Magnetic properties of planar nanowire arrays of Co fabricated on oxidized step-bunched silicon templates

Abstract

Planar nanowire (NW) arrays of Co grown on oxidized step-bunched Si(111) templates exhibit room temperature ferromagnetic behaviour for wire widths down to 25 nm. Temperature and thickness dependent magnetization studies on these polycrystalline NW arrays show that the magnetic anisotropy of the NW array is dominated by shape anisotropy, which keeps the magnetization in-plane with easy axis parallel to the wires. This shape related uniaxial anisotropy is preserved even at low temperatures (10 K). Thickness dependent studies reveal that the magnetization reversal is governed by the curling mode reversal for thick wires whereas thinner wires exhibit a more complex behaviour which is related to thermal effects and size distribution of the crystal grains that constitute the NWs.

Fabrication of flexible oriented magnetic thin films with large in-plane uniaxial anisotropy by roll-to-roll nanoimprint lithography

“…However, it can be seen that He's model and experimental data do not match well in the low temperature regime (< 100 K), in contrast to previous reports 28,36 . As an example, HC values at 10 K are about 50% higher than model predicted values.…”

“…al. 28 followed this technique to fabricate Co nanostripe thin films which exhibit room temperature ferromagnetism and large in-plane coercivities up to 920 Oe.…”

Magnetic and transport properties of epitaxial stepped Fe3O4(100) thin films

“…13 Most studies focus on anisotropy induced by step arrays, particularly metallic films on stepped surfaces, such as Fe on stepped Ag, 2-4 Au, 4 W, [5][6][7] and Si, 12 Fe 1Àx Co x on stepped GaAs, 8 Co on stepped Cu, 9,10 and CoPt 3 on stepped MgO. 11 However, the alignment of the magnetization easy axis, associated with this step induced anisotropy, is debatable.…”

Magnetization Reversal Behaviour of Planar Nanowire Arrays of Fe

“…It scales with KV, where K is the magnetic anisotropy per unit volume, and V the system's volume. This suggests that a possible route to overcome SP in the planar NW arrays is to either enhance K (e.g., by deposition on a heavy metal substrate [14]) or enhance V (by fabricating thick NW arrays [15][16]). …”

“…The latter approach has been successfully employed to produce room temperature (RT) ferromagnetic NW arrays using shallow angle deposition [15][16] and reactive deposition epitaxy techniques [12]. Considering the fundamental and applied interest in the magnetic nanostructrues, it is important to investigate the magnetization reversal processes in them.…”