Magnetic Heat Engine Possibility in the FutureCategory: Science & Technology
Posted: July 17, 2012 10:13AM
Many of the technologies we use every day put out heat as they operate, which wastes a great deal of energy. It should not be surprising then that researchers have been trying for some time to develop heat engines that will convert heat into something more useable, whether that be kinetic energy or electrical power. Now researchers at Ohio State University have discovered the "giant spin-Seebeck" effect, as they call it, which is a more powerful form of the spin-Seebeck effect which converts heat into electricity via magnetism.
First discovered in 2008, the spin-Seebeck effect, which is not well understood at the moment, occurs when heat induces a spin-current within a material. A spin-current is the transfer of spin states from one electron to another; similar to how an electric current is the transfer of energy from one electron to another. The induced spin-current generates a voltage which can be passed through a circuit then to do work.
The giant spin-Seebeck effect is similar to the spin-Seebeck effect but, well, bigger. The OSU researchers measured a voltage roughly 1000 times greater than the regular spin-Seebeck effect would produce. While this is definitely good news for the potential creation of a heat engine using this effect, there are some issues. The material the OSU researchers observed this in, a non-magnetic semiconductor, had to be cooled to between 2 K and 20 K and placed in a 3 Tesla external magnetic field, which is similar to that produced by an MRI machine. Neither of these conditions make the discovery immediately useful, but this could lead to new research to better understand the spin-Seebeck effect. We still may see a magnetic heat engine someday.