Topological Textures at Antiferroelectric Domain Walls

Antiferroelectric materials, of which PbZrO3 (PZO) is an archetype, are characterized by the anti-parallel ordering of their dipoles, and therefore their lack of overall polarization. Departures from such antipolar ordering can exist, however, around structural discontinuities such as domain walls. At least two distinct types of domain walls exist in perovskite PbZrO3: (i) antiphase boundaries -or, more generally, translational boundaries-, where the crystal axes do not change orientation but the antipolar sequence is shifted, such that, for example, it goes from ++-- to --++, and (ii) ferroelastic domain walls, where the crystal axes do change their orientation. These two types of domain walls are not mutually incompatible and can -often do- coexist. As we shall see, each of these types of domain walls can generate new polar topologies inside the otherwise colinear antipolar matrix.