Spontaneous polarization screening in a single domain ferroelectric

Abstract

The conditions of thermodynamic equilibrium in a single domain ferroelectric with and without electrodes are considered within the framework of phenomenological theory. The spontaneous polarization in such a ferroelectric can be screened by its intrinsic electrons and holes. The work functions on opposite faces of a c-domain ferroelectric plate differ by more than a width of the forbidden band of the material; on the negative face of the crystal the work function being less than the electron affinity of the substance (about 0.3 eV for BaTiO₃). In a short-circuited thermodynamically equilibrium ferroelectric capacitor the electrons and holes screening spontaneous polarization are located not on metal plates but within ferroelectric surface layers, the last conclusion is true for substances of BaTiO₃-type, having large values of spontaneous polarization.