Magnetic memories and microprocessors are an energy efficient dream -

Scientists at the University of California, People’s Republic of Berkeley, believe that future computers could well be magnetic, saving as much as a million times less energy than CMOS semiconductors.

Their analysis proposes creating microprocessors that use nanometre size bar magnets for all the switching required for both memory and logic.

The chips, should they come to pass, will dissipate 18 millielectron volts of energy at room temperature.

Jeffrey Bokor, UC Berkeley professor of electrical engineering and computer sciences think the idea is a real goer. "In principle, one could, I think, build real circuits that would operate right at the Landauer limit," he said.

The Landauer limit is the minimum according to the second law of thermodynamics.

Bokor, Brian Lambson and David Carlton presented a paper on the subject in the journal Physical Review Letters.

The nanomagnets the scientists are experimenting with are 100 nanometres wide and 200 nanometres long.  The north-south polarities in a magnet can represent 0 and 1.  Also, if multiple nanomagnets are coupled, the north and south poles can exhibit results similar to CMOS transistors using dipole-dipple interactions.

The big challenge, say the scientists, is getting the wiring and transistors working properly. "The magnetic technology we are working on looks very interesting for ultra low power uses," Bokor said. "We are trying to figure out how to make it more competitive in speed, performance and reliability. We need to guarantee that it gets the right answer every single time with a very, very, very high degree of reliability."

[The illustration, according to UC Berkeley: In magnetic contrast images (top) taken by the Advanced Light Source at Lawrence Berkeley National Laboratory, the bright spots are nanomagnets with their north ends pointing down (represented by red bar below) and the dark spots are north-up nanomagnets (blue). The six nanomagnets form a majority logic gate transistor, where the output on the right of the center bar is determined by the majority of three inputs on the top, left and bottom. Horizontal neighboring magnets tend to point in alternate directions, while vertical neighbors prefer to point in the same direction.]