INTERACTION OF FERROELECTRIC DOMAIN WALLS AND SHAPE OF EQUILIBRIUM REPOLARIZATION NUCLEI

The growth of a repolarization nucleus in an electric field is hindered by cohesive forces acting near its tips on the adjacent domain walls. They can reach large values when the distance between the domain walls becomes comparable to their thickness. It is shown that the cohesive forces are expressed in terms of the coefficients of the Ginzburg-Landau energy expansion, which includes a gradient contribution. For a uniaxial ferroelectric, an estimate of the maximum value of the internal field associated with the gradient interaction of the domain walls is obtained. Its relation to the internal coercive field E in the Ginzburg-Landau theory is E* /E = 3√3/8 ≈ 0.65.