Perturbation analysis and memory in ferroelectric materials

Many ferroelectric materials like LiTaO3 and LiNbO3 exhibit peculiar behavior in terms of showing a large discrepancy between experimental and theoretical values of coercive field by the use of Landau-Ginzburg model. If a perturbation is given at zero field, then there is also perturbation or fluctuation in polarization with respect to the nondimensional value of domain-wall width. An eigenvalue problem is deduced through a linear Jacobian transformation to show that there is a finite value of "memory," when the perturbation in the electric field is lifted. The eigenvalue gives a characteristic value of polarization, which also gives rise to a zone of stability for polarization. This perturbation formalism also allows the calculation of the limits of the coercive field and, subsequently, the values of the domain-wall width can also be estimated, which show both the lower and upper limits of theoretical values for both the above ferroelectric materials, deduced as the theoretical limits of the coercive fields. The theoretical framework is developed in this article. (C) 2004 American Institute of Physics.