Apparent dielectric hysteresis without significant dipolar movement?

Under suitable conditions, a hysteresis-type electric-field dependence of the current or of the polarization can be observed during poling of ferroelectric polymer films. But it is found here that the poling of nonpolar polymers which contain excess charges sometimes leads to a similar hysteresis behavior. In support of this finding, we present current measurements during the electric poling of α-poly(vinylidene fluoride) (α-PVDF) films and compare the results to the respective behavior of β-PVDF films in which charge effects play quite a different role