More bits per square inch

A recent development by University of Massachusetts researchers may someday enable consumers to store 25 full-length, DVD-quality movies on a disc the size of a penny. That amounts to a data storage density of about 1.2 trillion bits per square inch.

The Massachusetts team, led by Mark Tuominen of physics and Thomas Russell of polymer science and engineering, specialises in nanofabrication and they have invented a new technique for creating tightly packed arrays of magnetic nanowires.

The project relied on self-assembling, nanoscopic, polymer scaffolds known as ‘nano-templates.’ The templates, which resemble highly ordered honeycomb structures, enable the researchers to ‘grow’ arrays of cobalt metal nanowires using a process called electrodeposition, said Tuominen.

The scientists can fill microscopic tubes with metal, creating nanowires that are 14 nanometers in diameter. Such readily fabricated and well-controlled arrays of magnetic elements are said to have great potential in magnetic data storage, claim the scientists.

The team induced a group of short copolymer nanocylinders to self-assemble within the polystyrene matrix. They then exposed the structure to ultraviolet light and used a chemical rinse, which resulted in a thin polystyrene film riddled with regularly spaced pores.

The scientists then used electrodeposition to grow metallic wires through the pores, yielding a densely packed nanoarray.

The Massachusetts team point out that the polymer template fabricating technique is quite general and could also be used for fabricating other array devices with nanoscale dimensions. Alternatively, the pores could also function as nanoreactors, holding catalysts for chemical reactions.

The research was funded by a National Science Foundation ‘Partnership in Nanotechnology’ grant, the Materials Research Science and Engineering Centre, and the US Department of Energy.