Theory of interface structures in double-layer ferroelectrics

Interface structures in double-layer ferroelectrics comprising two distinct layers of different polarization properties, with bilinear interface coupling across the interface, are examined analytically within the framework of Landau-Ginzburg phenomenological theory. The structures are investigated for coupled layers with: (i) one layer in paraelectric phase and the other in ferroelectric phase (ferroelectric-paraelectric), and (ii) both layers in ferroelectric phases (ferroelectric-ferroelectric). The effects of interfacial coupling on the total interface structure energies, interfacial coupling energies and mismatch in polarization across the interface are discussed.