Seebeck effect of weak links in a high-Tc superconductor

The authors have observed experimentally the analog of the superfluid helium fountain effect in a polycrystalline YBaCuO film. In a superconductor a temperature gradient induces the counterflow of superconducting electrons and quasiparticles. The supercurrent creates a phase difference at the intra- and intergrain weak links. In the presence of a temperature gradient parallel to an electric current they have detected an asymmetry of the current-voltage characteristic. Reversing the direction of the temperature gradient also reverses the sign of the current asymmetry. They estimate the thermoelectric coefficient for the quasiparticles in the YBaCuO sample.