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.
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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