Tuesday, October 7, 2008
Hot Topics - Redirecting magnetization for better memories
Scientists in Japan have opened the way to devices that could combine data processing with non-volatile memory — memory that retains its contents without a power supply.
Hard-disk drives and magnetic memory devices rely on processes that involve switching magnetization direction, a feat normally achieved by applying a current-generated magnetic field. As described in this week’s edition of Nature, the team of scientists has instead used an electric field to directly control the magnetization direction in a semiconductor.
Until now, using electric fields to manipulate magnetization in a semiconductor was possible only after resorting to mechanically generated strain, which is far from suitable for practical applications.
To achieve purely electrical control, Hideo Ohno from Tohoku University in Sendai, Japan, and his colleagues used a ferromagnetic semiconductor whose magnetic properties were coupled to its concentration of charge carriers. They were then able to manipulate the magnetic direction in response to an applied electric field that altered the carrier concentration.
Ohno and colleagues suggest that their findings could lead to “a totally new scheme of non-volatile device operation, without resorting to the use of a magnetic field, spin current or mechanical stress.”