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“Background Porous anodic aluminum oxide (AAO) attracted a remarkable interest due to the pioneer work of Masuda and Fukuda [1]. Self-organized nanoporous structure with hexagonal ordered morphology can be obtained on a highly pure Al surface via electrochemical anodization in acidic medium [1, 2]. AAO is extensively applied in the fields of biosensor

[3] and biofiltration [4] and as a nanotemplate [5, 6] for the fabrication selleck products of secondary nanostructured materials. AAO templates have many advantages over the polycarbonate membranes like high pore density, thermal stability, cost effectiveness and versatility. Pore diameter, length, inter-pore spacing, and pore ordering can be easily tailored by tuning the anodizing parameters such as voltage, time, electrolytes, pH value, and temperature. One-dimensional (1D) nanostructured materials such as nanowires, nanorods, and nanotubes play a special role in the field of nanoscience and nanotechnology due to their high aspect ratio (length/diameter) and large surface area. Ferromagnetic (Fe, Co, Smad family Ni) nanowires gain a lot of attention of scientific community in the last few decades due to their potential

application in the fields of ultra-high density magnetic storage [7], magnetio-electronics [8], high sensitive giant magnetoresistance (GMR) sensors [9, 10]. Co–Ni is an important type of binary ferromagnetic alloys having high mechanical strength [11], good wear resistance [12], anti-corrosive performance [13], and electrocatalytic activity [14, 15]. Moreover, the standard electrochemical potentials of Co2+ and Ni2+ almost have the same value of −0.28 and −0.23 V, respectively, so Co–Ni binary alloy nanowires can be easily fabricated in the nanopores of AAO template by co-electrodeposition.

Information technology made much progress especially in the last few years, which reflects the interest of the researchers and investment of companies in this field. A decade ago, the limit of areal density was about few 10 gigabits (GB)/in.2[16]. Today, the limit reached to several hundred GB/in.2. Terabit (TB) hard disk is already available commercially, and a number of companies are in competition to increase the capacity and decrease the size of the hard disk [17]. The areal density has been increased using nanomagnet, in which 1 bit of information corresponds click here to a single-domain nanosized particle. One simple and economical way of achieving nanomagnetic arrays over a large area is based on highly ordered AAO templates [16]. Up till now, several methods have been applied to fill the pores of AAO template with metallic or magnetic nanowires like sol–gel [18], chemical vapor deposition [19], electroless deposition [20], and electrochemical deposition [5]. Electrochemical deposition is the most simple, efficient, versatile, and cost effective technique. It is well known that anodization of metals is always associated with an insulting barrier layer between the metal substrate and metal oxide film [21].