  The equilibrium domain structure and its evolution under an electric field in
ferroelectric bilayers and graded multilayers are considered. The equilibrium
bilayer is self-poled and contains a single-domain and a polydomain (with 180
domains) layers. The polarization of a graded multilayer proceeds by movement
of wedge-like domains as a result of progressive transformation of polydomain
layers to a single-domain state. The theory provides the principal explanation
of peculiarities of dielectric behavior of graded ferroelectric films and can
be applied to graded ferromagnetics and ferroelastics.
