Detailed Study of Switching Current in Barium Titanate

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Abstract
The polarization reversal process in ferroelectrics has, up to now, been characterized solely by the total switching time and the maximum value of the switching current. The work presented in this paper was aimed at determining how the instantaneous value of the switching current in single crystals of BaTiO3 depends on the applied field, the state of net polarization of the crystal, and possibly other factors. It has been found that the switching current density can be expressed as the product of a function of the polarization, φ(p), and a function of the electric field, exp(−α/E). The form of the function φ(p) indicates a predominance of sideways expansion of 180° domains, with an exponentially increasing domain wall velocity. This last result is shown to be in agreement with a picture of domain wall motion by nucleation of new domain wall layers. This interpretation, together with some details of the switching current pattern, suggests that a crystal, although apparently single‐domain, may always retain some small domains of opposite polarization.