Prediction of a giant dielectric anomaly in ultrathin polydomain ferroelectric epitaxial films

The amplitudes of electric-field-induced translational vibrations of 90 degrees domain walls formed in a tetragonal ferroelectric thin film grown on a cubic substrate are calculated theoretically. The domain wall contribution to the dielectric response of an epitaxial film is evaluated and shown to be important in common heterostructures. In some special film/substrate systems this contribution must increase rapidly with decreasing film thickness, which may result in a giant dielectric anomaly.