Fabrication and applications of nanocomposite structures using anodized aluminum oxide membranes

As the field of nanotechnology continues to advance and device feature sizes scale down to ever smaller dimensions, it is becoming increasingly important to develop quick and efficient methods for large-scale production at the nanoscale. Creating such a template would have widespread uses in areas such as magnetic data storage, chemical sensors, and mask technology. One promising approach to realizing this goal may lie in utilizing the self-ordering behavior found in porous anodized aluminum oxide (AAO). This material offers many advantages such as the ability to customize the pore diameter and spacing and easy device integration based on its compatibility with silicon substrates. The pores of the AAO templates can be filled with many different materials via electrochemical deposition or other methods to produce numerous potential devices. In this work, current research results detailing the fabrication of AAO templates and their use in creating ̃100 nm tall CoPt, Ni, and composite Ni/CoPt nanowires is demonstrated. The synthesis of such nanostructures may ultimately be advantageous for new types of patterned magnetic recording media. The Ni nanowires exhibit relatively soft magnetic coercivity of 242 Oe, while the CoPt nanowires show a very high coercivity of at least 10.97 kOe, measured in the perpendicular direction along the nanowires axis. The composite soft magnet / hard magnet Ni/CoPt nanowires exhibit intermediate perpendicular coercivities depending on the relative amounts of Ni and CoPt. The Ni80nm / CoPt20nm nanowires showed a coercivity of 1.96 kOe, the Ni50nm / CoPt50nm nanowires had a coercivity of 3.59 kOe, and the Ni20nm / CoPt80nm nanowires had a coercivity of 5.10 kOe. This marked decrease in the coercivity is significant because it could facilitate easier magnetic data writing. Analysis of the magnetic properties of the various nanowire structures and their dependence on the processing parameters is presented. A method for utilizing the AAO structure to replicate a master stamp for nanoimprinting technology is also discussed. In addition, plans for future work and a discussion of the application of these fabricated structures towards magnetic recording technology are presente