Template-based Synthesis and Characterization of High-density Ferromagnetic Nanowire Arrays

This chapter covers the synthesis and characterization of magnetic nanowire arrays that are grown inside nanoporous templates. Applications for such arrays include patterned recording media, magnetic and acoustic sensors, and other avant-garde applications that will be envisioned once the fundamental properties and performances of these arrays are better known. Several nanoporous templates are introduced, but this chapter primarily focuses on results using anodic alumina templates. The templates are filled with ferromagnetic metals via electrodeposition either using DC deposition onto an electrode after the removal of a barrier oxide or using AC deposition to eliminate the need to remove the oxide. Several typical electrolyte recipes are given (Co, Fe, FeGa alloys, Ni, and NiMn), and the details of both techniques are discussed. Methods for controlling the magnetic properties of the arrays by the choice of nanowire material, diameter, and interpore spacing, in addition to external fields, are detailed. Next, numerical simulations are presented in order to investigate the switching behavior of magnetic nanowires. Perfect hexagonal arrangements of pores on a square centimeter scale are demonstrated using imprint lithography. Finally, the applications of recording and sensors are discussed in detail.