YBCO thin films on ferroelectric substrates: the polarization-induced changes of superconductive properties

The influence of spontaneous polarization of a ferroelectric substrate on the electrical properties of YBCO films was studied. Both the superconducting transition temperature and the resistance in the mixed state were changed with polarization reversal. The largest changes were observed in the films deposited onto LiNbO3 plates with an opposite direction of spontaneous polarization. The nature of this effect and its comparison with the electric field effect in superconductors are discussed.