DOMAIN-WALL CONTRIBUTION TO THE PIEZOELECTRIC RESPONSE OF EPITAXIAL FERROELECTRIC THIN-FILMS

Domain-wall contribution to the longitudinal piezoelectric coefficient d(33) is calculated theoretically for prepolarized tetragonal ferroel ectric thin films epitaxially grown on cubic substrates. To that end, translational vibrations of ferroelastic 90 degrees domain walls induc ed by a weak measuring electric field are analyzed in the typical case of a laminar c/a/c/a domain structure, The average orthogonal displac ement of the film free surface caused by collective domain-wall moveme nts is calculated by the method of effective dislocations. On this bas e the domain-wall contribution Delta d(33) to the converse piezoelectr ic effect is evaluated and shown to be substantial in common heterostr uctures. (C) 1997 American Institute of Physics. [S0003-6951(97)01351- X].