Order-Parameter Symmetries of Domain Walls in Ferroelectrics and Ferroelastics

摘要

The symmetry of boundaries between ferroelectric, ferroelastic and antiphasedomains is a key element for a theoretical understanding of their properties.Here, we derive this symmetry from their organic relation to the symmetry ofthe primary transition order parameters. The domain wall symmetries are shownto coincide with directions of the order-parameter n-dimensional vector space,corresponding to sum of the vectors associated with adjacent domain states.This property is illustrated by the determination of the domain wall maximalsymmetries in BaTiO3, LaAlO3, SrTiO3 and Gd2(MoO4)3. Besides, the domainpattern in YMnO3 is interpreted as resulting from an annihilation-creationprocess, the annihilation of the antiphase domain walls creating sixferroelectric domain walls merging at a single point.