First order reversal curves and hysteresis loops of ferroelectric films described by phenomenological models

The increasing parts of the non-symmetric P(E) hysteresis loops of PZT ferroelectric films (First Order Reversal Curves - FORC), were used in order to calculate the FORC distribution in which a separation of the reversible and irreversible contributions to the polarization was obtained. The role of the frequency of the applied field on the switching properties of the ferroelectric films were analyzed by this method. A phenomenological model was used to describe the P(E) hysteresis loops. Using the model parameters determined from the fit of P(E) major loops, minor loops and the FORCs were simulated, at various frequencies and amplitudes of the applied field. The calculated FORC diagram was compared with the experimental one and the limits of the model were discussed.