A renowned group of researchers has testified after their research that local thermal perturbations of spins in a solid can transform heat to energy even in a paramagnetic material – where spins were assumed to be incapable of correlating for to do so.
This effect, which the researchers termed “paramagnon drag thermopower,” transforms a temperature variation into an electrical voltage. This discovery could lead to a much more efficient thermal energy harvesting. A case in point to look at could be transforming car exhaust heat into electric power to increase fuel-efficiency. Or even fueling smart clothing by using body heat.
The scientific group consists of eminent scientists from the University of North Carolina State, the Department of Energy’s Oak Ridge National Laboratory (ORNL), the Chinese Academy of Sciences and the Ohio State University.
In solids with magnetic ions (e.g., manganese), thermal perturbations of spins, there are two possibilities— either they align or they don’t. However, spins are not exactly random in occurring: they create temporary, short-range, locally measured structures – paramagnons – which only stay for a millionth of a billionth of a second and go across over only two to four atoms.
In a new paper talking about the work, the researchers explain that despite these faults, even paramagnons can freely move in a temperature variation and force-free electrons along with them, propelling paramagnon drag thermopower.
“Behons the Néel temperature, you would think the thermopower being created by the spin waves to go down,” says Daryoosh Vashaee, professor of electrical and computer engineering and materials science at NC State and one of the corresponding authors of the paper talking about the work. “Bur, we didn’t observe the expected drop off, and we were determined to know why.”
The research is published in Science Advances and is funded by many organizations like the National Science Foundation, the Air Force Office of Scientific Research, etc.