"This level of areal density will turn the heads of the disk-drive community to the potential of this technology," said Brendan Hegarty, chief executive officer of NanoMagnetics. "We will be having discussions with members of the industry as to possible partnerships."

NanoMagnetics's method of creating magnetic nanomaterials is based on the protein molecule ferritin. Normally, animals, plants and bacteria use ferritin molecules to store iron in the form of iron oxide. But NanoMagnetics has developed a set of chemistries that allow it to put metal alloys, in particular cobalt-platinum, inside ferritin molecules.

A key advantage of ferritin molecules is that they are always the same size - effectively a "12 nm diameter cage with an 8 nm cavity". NanoMagnetics uses these molecules as "organic templates" that limit the diameter of the metal-alloy grains created inside them to a maximum of 8 nm.

Once the alloy nanoparticles have been made, they are coated onto standard glass disk substrates by spin- or dip-coating. Then the film is annealed to cause a phase transition and alignment of the particles - a process that optimizes their magnetic properties and also converts the ferritin molecules to carbon.

NanoMagnetics says it demonstrated the 6 Gbit/square inch recording density on commercial glass substrates without the aid of an electronic channel or error correction, and claims that the result would represent an even higher density within a disk drive.

To achieve a recording density of 6 Gbit/square inch, the company refined the crystalline properties of its magnetic inks and improved the quality of its films, working in collaboration with the University of Manchester, UK. NanoMagnetics's previous best recording density was 2.2 Gbit/square inch.

NanoMagnetics chief technology officer Eric Mayes will present the results at the Magnetic Recording Conference (TMRC) in the US in August.