Thermoelectric effects in superconductors

It is a pleasure and an honour for me to speak before this highly esteemed audience. The subject of my talk is devoted to thermoelectric effects in superconductors. The question of whether thermoelectric phenomena can be observed in metals in the superconducting state was raised more than 50 years ago, but first attempts to observe such effects as Seebeck electromotive force, or Peltier heat, or Thomson heat, failed to reveal any trace of the existence of these effects in superconductors. In any case, it was definitely shown that these effects, if they exists are weaker by many orders of magnitude, than the analogous effects in normal metals. This was especially clearly demonstrated by the experiment of Steiner and Grassman in 1935,1 who tried to observe a Seebeck electromotive force in superconductors. These authors suspended a superconducting bimetallic ring on a torsion wire placed in a weak external magnetic field and heated the ring. If a Seebeck thermo-electromotive force would arise, as it arises in a case of normal metals, then this force would induce acceleration of superconducting electrons and the current in the ring would increase with time, leading to a torque on the wire, which it might be possible to observe.