New Way To Capture Heat and Turn It into Electricity

Credit: OSU

Magnets are a crucial part of collecting energy from heat: When one side of a magnet is heated, the other side—the cold side—gets more magnetic, producing spin, which pushes the electrons in the magnet and creates electricity.

The paradox, though, is that when magnets get heated up, they lose most of their magnetic properties, turning them into paramagnets—“almost-but-not-quite magnets,” Heremans calls them. That means that, until this discovery, nobody thought of using paramagnets to harvest heat because scientists thought paramagnets weren’t capable of collecting energy.

What the research team found, though, is that the paramagnons push the electrons only for a billionth of a millionth of a second—long enough to make paramagnets viable energy-harvesters.

The research team—an international group of scientists from Ohio State, North Carolina State University and the Chinese Academy of Sciences (all are equal authors on this journal article)—started testing paramagnons to see if they could, under the right circumstances, produce the necessary spin.

What they found, Heremans said, is that paramagnons do, in fact, produce the kind of spin that pushes electrons.

And that, he said, could make it possible to collect energy.

Ohio State graduate student Yuanhua Zheng is also an author on this work. The research was conducted in partnership with additional researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory and was supported by the National Science Foundation, the Air Force Office of Scientific Research and the U.S. Department of Energy.

Contacts and sources:
Laura Arenschield
Ohio State University

Citation: Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe. Y. Zheng, T. Lu, Md M. H. Polash, M. Rasoulianboroujeni, N. Liu, M. E. Manley, Y. Deng, P. J. Sun, X. L. Chen, R. P. Hermann, D. Vashaee, J. P. Heremans, H. Zhao. Science Advances, 2019; 5 (9): eaat9461 DOI: 10.1126/sciadv.aat9461