Producing electricity from temperature gradients using transverse spin current

Thermoelectric generators depend on temperature differentials to produce electricity and enjoy widespread use in satellites, space probes, and other applications. Most operate via the Seebeck effect, where a temperature gradient is directly converted into an electric voltage. Recent research has explored thermoelectric generators that operate using other effects, such as the anomalous Nernst effect or the spin Seebeck effect.

Fujimoto and Ogata proposed a type of thermoelectric generator operating under an alternate mechanism: transverse thermo-spin conversions.

“We theoretically demonstrate a large thermoelectric power generation based on the novel mechanism in which a temperature gradient converts into a perpendicular electric voltage by using spin degree of freedom,” said author Junji Fujimoto.

The alternative mechanism features two different thermo-spin conversions working in tandem. The first, the spin Nernst effect, converts a temperature gradient directly into a transverse spin current. The second conversion is a combination of two effects and works by converting a temperature gradient into electromotive force via the Seebeck effect and then into a transverse spin current via the spin Hall effect.

The researchers hope power generation via transverse spin currents could become an effective and widespread means of supplying electricity to nanoscale devices. The next steps for the researchers are to test their theoretical mechanism experimentally and expand the possible materials that can be used.

“The results are obtained for a specific material, bismuth, which generates a lot of power,” said Fujimoto. “Generalizing the mechanisms behind that power will lead to an instructive law for more efficient device application.”

Source: “Thermoelectric power generation via transverse thermo-spin conversions,” by Junji Fujimoto and Masao Ogata, Applied Physics Letters (2022). The article can be accessed at https://doi.org/10.1063/5.0077158 .

This paper is part of the Thermoelectric Materials Science and Technology Towards Applications Collection, learn more here .