Magnetic nanowires fabricated by anodic aluminum oxide template—a brief review

Abstract

Anodic aluminum oxide (AAO) with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into the nanopores produces AAO embedded nanowire arrays. Whilst the templates can be further removed to obtain free individual nanowires, the embedded nanowires form an interesting nanocomposite structure. Recent research activities on the fabrication and characterization of AAO template based magnetic nanowires are reviewed in this article. Studies of specific systems are given as an example of the research in the area. anodic aluminum oxides, electrochemical deposition, magnetic nanowires, templates, magneto-optical propertiesPACS: 75.75.+a, 81.07.-b, 82.45.Aa, 75.50.-y Using a diverse range of fabrication techniques, magnetic nanostructures have been fabricated in a variety of forms: nanoparticles [1,2], nanowires [3], porous nanotubes [4] hollow spheres [5,6] and lithographically patterned films. In this article, we focus on magnetic nanowires fabricated using anodic aluminum oxide (AAO) templates.AAO templates are attractive in nanowire fabrication because of their excellent physical properties. The templates are regular, monodispersed and highly ordered (as shown in Figure 1) and are produced by a self-organized electrochemical process. The pore diameters (typically achievable in the range of 5 to 250 nm) and depths (a few nanometers to hundreds of micrometers) are controllable with high areal densities (10 8 -10 11 pores/cm 2 ), providing significant flexibility in the growth of nanowires with various diameters and aspect ratios. AAO templates are also transparent in the optical spectrum, from near ultraviolet (UV) to near infrared (IR), which makes them a suitable host for the investigation Figure 1 An electron micrograph showing highly ordered AAO template.of optical and magneto-optical properties of composite magnetic nanostructures. They are also thermally stable up to 900-1000°C, offering the possibility of thermal treatment of the magnetic nanowire arrays. In addition, they are corrosion-resistant and environmentally safe. Hence the templates have been used for producing nanowires of a very wide range of materials, including metals, semiconductors,

Recent Progress of Fabrication, Characterization, and Applications of Anodic Aluminum Oxide (AAO) Membrane: A Review

“…Nanostructures ranging from nanotubes, nanowires, nanorods, nano dots arrays, interconnected 3D nano networks with highly controllable size and shape of a certain material can be grown using such membranes [69,70] Successive deposition of specified material into the nanosized pores of the AAO membrane results in nanostructures embedded in the membrane. However, free nanostructures can also be obtained by removing the membrane acting as a template [71,72].…”

Growth Orientation Control of Co Nanowires Fabricated by Electrochemical Deposition Using Porous Alumina Templates

“…Metallic nanowire arrays created by electrochemical deposition using regular nanochannel templates have stimulated keen research interests in recent years. − These materials are characteristic of high length-to-diameter aspect ratios (typically greater than 1000), small lateral dimensions (typically 50–90 nm), and high population density (typically 10 8 wires/mm 2 ) or large numbers (typically in the order of 4 × 10 9 over an area of 5 × 5 mm) can be fabricated in rare or complex substructures, like single crystals, , bamboo structures, or core/shell structures . In addition to the above, there is also the possibility to create a large quantity of metallic nanowires of near perfect, defect-free crystal structures, which have the potential to approach the theoretical limit of metallic bonds for materials strength and elasticity.…”

Self-organization and FORC-based magnetic characterization of ultra-high aspect ratio epitaxial Co nanostrips produced by oblique deposition on an ordered step-bunched silicon surface

“…To prepare NWs and NSs, a variety of techniques based on self-organization, lithographic patterning or their combinations are intensively employed in many laboratories. An example is the electrodeposition of magnetic materials into anodized aluminum oxide templates, which is widely used due to its simplicity, low cost, and good nanostructure quality [17,18]. However, NWs are packed within a matrix of aluminum oxide, which limits the range of possible operations.…”