Press releases
Please quote Nature Materials as the source of these items.
July 2003
Small magnetic islands are more stable
The information on your computer hard drive is stored in magnetic structures known as domains. To cram more data onto the same disk area, engineers are continually decreasing the size of these domains. At some point, however, the stability of the domains becomes an issue, representing a potential limit to size reduction. In the August issue of Nature Materials, Harald Brune and colleagues in Switzerland show how to increase the stability of small magnetic structures.
One of the factors that affects domain stability is the 'magnetic anisotropy energy' - the bigger the anisotropy the more stable the magnetic data. Brune and colleagues have discovered that for small magnetic islands on a flat surface, the size of the magnetic anisotropy is dictated almost exclusively by the atoms at the edges of the islands. As small islands have proportionally more edge atoms than large islands, their magnetic anisotropy is consequently much higher.
To date, this effect has only been seen at cool temperatures, down to -223 Celsius. So the size of the magnetic 'domains' investigated by Brune and colleagues — around 1,000 atoms or less — will not be appearing in your computer hard drive anytime soon. Nonetheless, these experiments indicate new ways to control the magnetic behaviour of small structures at these scales.
