Material helps bits beat heat

The usual way to cram more information onto magnetic disks is to make the bits that store the 1s and 0s of digital information smaller.

This has worked for the past several decades, but the usual methods will hit up against the laws of physics when magnetic bits become small enough that heat energy overcomes the magnetic energy that keeps atoms aligned.

Researchers from the University of Delaware, the French National Scientific Research Center (CNRS), and the Independent University of Barcelona (UAB) in Spain have discovered a way to shore up magnetic energy that promises bits only a few nanometers across -- the span of a few dozen hydrogen atoms.

The method could make it possible to store more than a trillion bits per square inch, according to the researchers.

They found that coupling ferromagnetic nanoparticles to an antiferromagnetic material increased the nanoparticles' magnetic energy, making them less susceptible to thermal fluctuations. The atoms in both types of materials are magnetically aligned, but the antiferromagnetic alignment alternates by atomic row, canceling out the magnetism.

The method could be used to make practical devices soon, but probably won't be necessary for five to ten years, according to the researchers. The work appeared in the June 19, 2003 issue of Nature.