`Self-assembling’ magnetic materials

IBM scientists have developed a class of magnetic materials that may one day allow computer hard disks to store more than 100 times more data than they do today.

The researchers have discovered reactions that cause tiny magnetic particles, each uniformly containing only a few thousand atoms, to automatically arrange themselves into well-ordered arrays with each particle separated from its neighbours by the same preset distance.

The reactions also permit precise control of both the size of these nanoparticles and their separation distance, factors that are important in increasing data density.

The nanoparticles are made through combining iron and platinum-containing molecules in a heated solution. As the molecules react, the iron and platinum separate from their organic segments and coalesce into spherical nanoparticles of an iron-platinum alloy, each containing thousands of atoms in equal proportions.

Surrounding the growing nanoparticles is a flexible layer of surfactant molecules that, like spokes extending in all directions from the centre of a ball, keep the particles physically and magnetically independent as they self-assemble into a regular array as the solvent is allowed to evaporate.

Further heating in the absence of oxygen bakes the surfactant coating around each particle into a hard carbon shell that locks the particles into place. This heating also causes a critical change in the atomic structure within each particle: The iron and platinum atoms rearrange themselves from a useless form that does not retain its magnetic orientation to a useful one that does.

Smaller magnetic particles enable smaller data bits, and in general, uniform particle size permits easier and more accurate detection of smaller data bits.

There are many unknowns to be studied before the new material can be considered for practical use, and even then the benefits will have to outweigh the costs of installing new equipment and making changes in existing manufacturing processes.

Looking further into the future, researchers are optimistic about this process facilitating the ultimate in data-storage density: storing one data bit in a single tiny grain of magnetic material rather than the several hundred to 1,000 grains used today.

Copyright: Centaur Communications Ltd and licensors