MadSci Network: Physics

Re: Does the thermoelectric effect exist in superconductors?

Date: Wed Nov 24 14:35:34 2004
Posted By: Joseph Weeks, Engineer
Area of science: Physics
ID: 1097515902.Ph

What an interesting question. The Seebeck effect, named after Thomas Seebeck is the observation that when two dissimilar electrical conductors are connected at two points, and there is a temperature difference between the two points, an electrical current flows between the two points. A good discussion of Seebeck's history can be found here.

Seebeck observed that when copper and bismuth wires were connected at two ends, and one end was heated with respect to the other, a magnitized needle was deflected. At the time, the relationship between electricity and magnetism was not always well understood. Seebeck reasoned that, because of this thermoelectric effect, the magnetic field of the earth was caused by the temperature between the poles of the earth and the equator. Although he was wrong, his discovery that dissimilar metals produce an electrical potential is the basis for most high temperature measurement, and is used to verify that the pilot light is on in your water heater.

So, I did a little Google search to attempt to answer your question. And yes, it appears that joints between normal and superconductors do, indeed exhibit a Seebeck effect. Keithley Instruments provides an application note about measuring the resistance of superconductors Automatic Resistance Measurements on High Temperature Superconductors . They state "However, the connection to the (superconductor) sample will inevitably create a thermocouple junction." These folks know as much about electronic instrumentation as anyone in the business, so that statement alone provides enough evidence to convince me. You can, if interested, find books that deal with the Seebeck effect in superconductors, such as Theory of High Temperature Superconductivity . Other researchers have published information concerning the Seebeck effect in superconductors such as Seebeck effect of weak links in a high-Tc superconductor , A review of contemporary theoretical investigation of Seebeck effect origination in isotropic semiconductors , and Nonlinear Seebeck effect in a model granular superconductor .

I hope that helps to answer your question. Thanks for asking.

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