Ferromagnetic Nanowires for Nonreciprocal Millimeter-Wave Applications: Investigations of Artificial Ferrites for Realizing High-Frequency Communication Components

As far back as the 1850s, workers applying decorative and anticorrosive coatings of metallic surfaces used a technique [1] that would later be referred to as anodic aluminum oxide (AAO) synthesis. About 100 years later, the morphologies of such coatings were investigated and found to consist of highly ordered/quasiregular arrays of high aspect ratio nanopores [2]. During the same decade, nuclear scientists detected the tracks of energetic heavy ions in polymer membranes, and, by the 1960s, chemical etching of ion tracks was used as a standard nuclear diagnostic [3], [4]. Although track-etched polymer membranes offer arrays of nanopores with uniform diameters, the nanopore spacing is random. In the mid-1970s, ferromagnetic nanowires (FMNW).