Electricity loosens tiny bits

The key to cramming more data onto a disk or magnetic memory chip is decreasing the size of the magnetic bits that represent the 1s and 0s of computer information. This is becoming increasingly difficult, however, because as a bit gets smaller it has to be made stronger to remain stable, and as a consequence it takes more magnetic force to reverse, or flip, its magnetic poles between the states that represent a 1 and a 0.

Researchers from Tohoku University in Japan have found a way to make flipping small bits easier. The researchers' electrically-assisted magnetization reversal process weakens the magnetization of a ferromagnetic semiconductor's magnetization by applying a pinpoint electric field, making the magnetization of individual bits easier to flip.

In general, adding energy to a bit makes it easier to flip. This the reason cassette tapes sound wobbly after too much time in a hot car -- some of the information gets lost when bits randomly flip due to thermal energy.

After demonstrating the principle of the process, the researchers are working to make it practical by increasing the transition temperature of the ferromagnetic semiconductor material, which is currently considerably below room temperature.

The method could be used practically in five to ten years, according to the researchers. The work appeared in the July 10, 2003 issue of Science.