Certain strains of bacteria absorb iron to make magnetic nanoparticles that let them navigate using the Earth's magnetic field. The team have extracted the protein behind this process and used it to create magnetic patterns that can store data.

Hard drives are usually made by 'sputtering', in which clouds of argon ions are fired at a sheet of magnetic material, knocking off particles which are deposited as a thin film on a disc. Groups of these particles, called grains, form the magnetic regions on the drive, with around 100 grains corresponding to one bit.

Instead of granular media, the Leeds team produce bit-patterned media. They start with a gold surface coated in chemicals in a chessboard pattern so that one set of squares binds proteins and the other repels them. They then apply the magnet-producing protein and coat the surface with an iron solution, which the protein-covered squares convert into magnetic material.

Each magnetic square in bit-patterned media can store one bit. Each square the team have so far produced is around 20 micrometres wide, far too bulky to store data with a density comparable to today's hard drives. They now plan to test out nano-sized squares, much closer to existing drive density. Eventually, they hope to create a disk with a single iron particle per square, which will store as much as 1 terabyte of data per square inch - far beyond the capability of most hard drives.