Field-adjusted suppression of the switching polarization in ferroelectric PZT thin films with Pt-electrodes

A surprising non-cumulative effect of the degradation mechanism (fatigue) of the switched polarization (P_r^s), was observed in MOCVD and sol-gel prepared Pb(Zr_0.47Ti_0.53)O₃ (PZT) ferroelectric thin films capacitors (FECAP) with Pt-electrodes. This effect is a manifestation of the ability of the suppression mechanism of P_r^s to self-adjust to the fatiguing field. Experimentally this was shown by performing two consecutive fatigue procedures on the same capacitor. The field used in the first procedure was 15 MV/m, which corresponds to about two times the coercive field (E_c). During this procedure, P_r^s was reduced (fatigued) by approximately a factor of 10. For the successive fatigue, the field used was twice the first one, i.e., about 4×E_c. During the latter procedure, the previously suppressed P_r^s was first significantly recovered and then suppressed again as the FECAP would have been virgin and directly fatigued at E ≈4×E_c. From this remarkable feature and other related results it was concluded that the microscopic mechanism must have a substantial reversible character and the peculiarity to adapt to the used fatiguing field (field self-adjusting).