Hysteresis curves for ferroelectric crystals in a varying external field. Relaxation model

We propose a description of switching in ferroelectric crystals using the equations of relaxation processes taking into account the action of a varying external electric field. Exact analytic solutions to these equations are obtained for an arbitrary dependence of the relaxation time on the external field and an arbitrary time dependence of the external field. The resultant solution forms the basis of numerical analysis of coupling between the frequency of the sinusoidal external field and the shape of the hysteresis curves. The results of calculations are in qualitative agreement with experimental data.