Stress change in YBa2Cu3O7-delta close to the superconducting transition

Measurements on Au/Pb(Zr1-xTix)O-3/YBa2Cu3O7-delta (x=0.47,0) thin film capacitor structures on SrTiO3(001) reveal a jump up to approximate to30% in the dielectric constant of the ferroelectric Pb(Zr0.53Ti0.47)O-3 films, which starts about 10 K above the superconducting transition of the underlying YBa2Cu3O7-delta layer. We show that this can be understood by a stress release in the ferroelectric film which must be caused by a stress change in the high-temperature superconductor starting already significantly above T-c.