Anodic alumina template assisted growth of magnetic nanowire/nanodots

Chowdhury, P and Barshilia, Harish C and Rajam, KS (2011) Anodic alumina template assisted growth of magnetic nanowire/nanodots. Technical Report. National Aerospace Laboratories.

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Nanostructures like nanowires, nanorods, nanotubes and nanodots have generated interest for engineering and materials scientists, due to their unique properties and possible applications in the ever-growing field of nano-electronics. However, the challenges remain to grow highly ordered nanostructured materials in a cost-effective way. During this project, we have grown highly ordered porous alumina template with diameter varying from 50 nm to 150 nm and used them to grow magnetic nanodots, nanowires and nanotubes. AAO template assisted growth of cobalt nanowires and nanotubes were carried out using three different electrochemical routes. These techniques are pulsed electrodeposition, chrono-amperometry and direct constant current. Growth morphology of as grown nanowires were characterized using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis. The higher growth (3 m/min) rate of Co nanowire was observed by pulsed electrodeposition technique in comparison to other techniques and this also results in higher density and uniform in length as expected. Further studies of growth morphology of Co nanostructures were carried out with partially filled pore bottom of AAO template with sputtered Au and it helped to grow Co nanotubes under critical bath conditions. It was observed that low current density and pH of electrolyte are the important parameters for the growth of these nanotubes. Magnetic properties of Co nanowires measured using vibrating sample magnetometer showed anisotropic behavior with coercivity values of the order of Hc() = 106 G and Hc(//) = 410 G. Two dimensional nanodot arrays of magnetic materials were fabricated using ultra thin alumina membrane as a shadow mask in sputter deposition. Magnetic properties of these magnetic arrays have been studied. AmCo5/Co exchange spring magnet array show coercivity of the order of 2000 Oe with high in-plane anisotropy. With further tuning the properties, these two dimensional magnetic array show potential applications in magnetic storage media with high density recording.

Item Type: Monograph (Technical Report)
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
PHYSICS > Physics(General)
Depositing User: Dr. Harish C. Barshilia
Date Deposited: 11 Oct 2011 08:16
Last Modified: 11 Oct 2011 08:16

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