Asymmetry of the hysteresis loops for the Au/PbTiO3/YBa2Cu3O7−δ capacitor

Ferroelectric samples with Au/PbTiO 3 /YBa 2 Cu 3 O 7− δ (Au/PTO/YBCO) structures have been grown on SrTiO 3 (STO) substrate. The X-ray diffraction, the capacitance–voltage, and the hysteresis loop methods were used to investigate the samples' structure and ferroelectric properties. The results show that the ferroelectric coercive fields drifted towards positive voltage, and the drift is attributed to the stress at the interfaces of the Au/PTO and the PTO/YBCO.