Piezoelectric enhancement of (PbTiO₃)m/(BaTiO₃)n ferroelectric superlattices through domain engineering

The phase diagram of (PbTiO₃)m/(BaTiO₃)n ferroelectric superlattices was computed using the phase-field approach as a function of layer volume fraction and biaxial strain to tune ferroelectric properties through domain engineering. Two interesting domain structures are found: one with mixed Bloch-Néel-Ising domain wall structures and the other with stabilized monoclinic Mc phases. The polarization of the monoclinic Mc phase is able to rotate from out-of-plane to in-plane or vice versa under an electric field, and thus facilitates the domain reversal of rhombohedral domains. This contributes significantly to both reduced coercive fields and enhanced piezoelectric responses.