A joint research team from NIMS and the University of Tokyo has developed a new composite in which three-dimensional nano-interfaces are distributed throughout the material by coating the surfaces of magnetic-insulator powders with a metal and sintering them. Using this structure, the team succeeded in observing thermoelectric conversion driven by spins in an insulator, a phenomenon previously observed only at nanoscale thin-film interfaces, in a macroscale material.

This research was published in Nature Communications.

Thermoelectric conversion, which uses the vast amounts of waste heat and unused heat around us as electrical energy, is one of the key technologies for improving energy-use efficiency and achieving carbon neutrality. The spin Seebeck effect is a physical phenomenon discovered in Japan in 2008 in which applying a temperature gradient to a magnetic material enables thermoelectric conversion via spin currents.