Thermoelectric power generation using insulators

Sep. 27, 2010

Joint Research group of JAEA, Tohoku University, Delft University of Technology, Fudan University, and FDK Corporation has found a new method for thermoelectric power generation using magnetic insulators.

The Seebeck effect, in which an electric voltage is generated by a temperature gradient in metals or semiconductors, and related thermoelectric phenomena have recently drawn a significant interest since a thermoelectric device possesses several appealing features needed for the future technologies, e.g., quiet, reliable and environmentally friendly. A drawback of this phenomenon is however that it is realizable only in conductors, thereby leading to a low efficiency of the devices due to the energy loss by conduction electrons? heat transport, and limits the practical application of thermoelectric devices.

Using a prototypical magnet (yttrium iron garnet^?), this group have established a new principle that a generation of the magnetic-moment flow (spin current) by a temperature gradient, i.e., the so-called spin Seebeck effect, occurs in an insulating magnet even in the absence of conduction electrons. In the previous work, the group has already established another principle that one can convert a spin current flowing through a magnetic insulator into an electrical energy. Therefore, by employing these two principles, we can realize the insulator-based thermoelectric devices that have never been considered so far.
This research has an impact on a development of new thermoelectric devices that use insulators having a potential to achieve a low energy loss. It expands the freedom of the design and integration of thermoelectric devices, and leads to a development of an environmentally-friendly electric technologies.

This work is published in the British science journal ?Nature Materials? (online, September 26, 2010).

?Yttrium iron garnet
A compound having chemical formula Y₃Fe₅O₁₂. In this research, a La-doped sample (LaY₂Fe₅O₁₂) was used.