Closer to New type of Thermoelectric "Heat Engine"

Researchers who are studying a magnetic affect that converts heat into electricity have found a new way to increase this electricity thousand time over-a step that will make the technology more practical.

In the spin Seebeck effect the spin of electrons creates a magnetic field which is detected as voltage in the adjacent material. Ohio State university researchers have found a way to induce the same effect in non-magnetic semi-conductors and increasing it almost thousand times. The researchers have named the effect “giant Seebeck effect” and university will start providing patent of the technology.

The report was published in this week issue of the scientific journal Nature.


The voltages produced are usually tiny, but the researchers reported increasing the voltage per degree change of temperature from microvolts to millivolts, a thousand time increase in the voltage boosting the power 1 million times.

Joseph Heremans, Ohio Eminent Scholar in Nanotechnology, said that his team's ultimate goal is a low-cost and efficient solid-state engine that coverts heat to electricity. These engines would have no moving parts, would not wear out, and would be infinitely reliable, he added.

"It's really a new generation of heat engine," said Heremans, professor of mechanical engineering and professor of physics at Ohio State. "In the 1700s we had steam engines, in the 1800s we had gas engines, in the 1900s we had the first thermoelectric materials, and now we're doing the same thing with magnetics."

This research could enable electronic devices that recycle some of their own waste heat into electricity. In a computer, it could enable heat-powered computation, or, inversely, it could provide cooling.

Researchers around the world are working to develop electronics that utilize the spin of electrons to read and write data. So-called "spintronics" are desirable because in principle they could store more data in less space, process data faster, and consume less power. And the spin-Seebeck effect takes the notion of spintronics a step further, by using heat to induce a flow of spin "information," called a "spin current."