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Research According to the newly published research, a very large thermoelectric effect can be created in a structure combining a ferromagnet (F) to a thin superconductor film (S) via an insulator (I), and where the superconductor is in the presence of a spin-splitting field due to the presence of a ferromagnetic insulator (FI) or a magnetic field (B).
Image Credit: Courtesy Academy of Finland

Published on February 11th, 2014 | by James Ayre

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Improved Thermoelectric Conversion Efficiency Via Use Of Magnets & Superconductors

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February 11th, 2014 by
 
An interesting development has occurred in the field of thermoelectrics — it’s been found that very high thermoelectric conversion efficiencies can be achieved by utilizing the “proper” combination of magnetic metals and superconductors.

The findings are notable because previously most effective thermoelectric devices have been forced to rely on semiconductors — thanks to the fact that most metallic structures have poor thermoelectric performance.

According to the newly published research, a very large thermoelectric effect can be created in a structure combining a ferromagnet (F) to a thin superconductor film (S) via an insulator (I), and where the superconductor is in the presence of a spin-splitting field due to the presence of a ferromagnetic insulator (FI) or a magnetic field (B). Image Credit: Courtesy Academy of Finland

According to the newly published research, a very large thermoelectric effect can be created in a structure combining a ferromagnet (F) to a thin superconductor film (S) via an insulator (I), and where the superconductor is in the presence of a spin-splitting field due to the presence of a ferromagnetic insulator (FI) or a magnetic field (B).
Image Credit: Courtesy Academy of Finland

The new findings were made by researchers from the University of Jyväskylä, Aalto University (Finland), San Sebastian (Spain). and Oldenburg University (Germany).

The Academy of Finland explains the work and provides context:

The electronic structure of semiconductors and superconductors looks superficially similar, because both contain an “energy gap,” a region of energies forbidden for the electrons. The difference between the two is that doping semiconductors allows moving this energy gap with respect to the average electron energy. This is in contrast to superconductors, where the energy gap is symmetric with respect to positive and negative energies, and therefore the thermoelectric effect from positive energy electrons cancels the effect from the negative energy electrons.

In the work published yesterday Heikkilä and the international research group showed how this symmetry can be broken by the presence of an extra magnetic field, and driving the electric current through a magnetic contact. As a result, the system exhibits a very large thermoelectric effect.

Something that is important to note is that since current superconductors all require extremely low temperatures these findings won’t have any immediate applications in consumer devices. The researchers think, though, that this mechanism “could be used in accurate signal detection, or a similar one could be applied in semiconductors to improve their thermoelectric performance.”

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.



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