Metal atoms make silicon magnetic

Researchers and manufactures routinely dope, or add impurities too, semiconductors like silicon to give the material specific electrical properties. Researchers are also working out ways to dope silicon to control its magnetic properties.

Devices made from magnetic semiconductors can make use of the spin of the electron in addition to its charge. These spintronics devices are potentially faster and consume less power than today' electronics.

Researchers from the State University of New York at Albany have found a way to make silicon ferromagnetic at room temperature. Ferromagnetic materials respond strongly to magnetic fields and remain magnetic after an external magnetic field has been removed. This opens the door to developing spintronics devices using the material of computer chips, which is easily manufactured using existing facilities.

The researchers implanted silicon with manganese ions to make a material that retains its ferromagnetic properties at temperatures as high as 127 degrees Celsius. The researchers doped the silicon at two concentrations of manganese: 0.1 percent and 0.8 percent. They found that the level of magnetism depends on the concentration of manganese, the temperature, and whether the silicon has been doped to be a positive or negative charge carrier.

The researchers' next steps are to more fully understand the electronic and physical structure of the material in order to determine the origin of the ferromagnetism.

The device could be ready for practical use in five to ten years, according to the researchers. The work appeared in the January 4, 2005 issue of Physical Review B.