Dipole-dipole interaction and domain relaxation of ferroelectric triangular lattice

In ferroelectric lattices, dipole arrangements are controlled by manipulating structural formation and orientations of ferroelectric thin films are determining factor to control dipole arrangements. Herein, tetragonal PbTiO₃ (PTO) thin films were obtained and triangular lattice is observed in (111)-PTO thin films. We used pulsed laser deposition and compared (001)- and (111)-PTO thin films. To confirm structural characteristics, X-ray diffraction patterns and second harmonic generations were used. In addition, dipole arrangements are investigated by using transmission electron microscopy. In particular, directions of dipoles are gradually changed and vortex-like domain structure is obtained in the (111)-PTO thin films. It is induced by tilting characteristics of polarization axes of the (111)-PTO thin films. To study domain relaxation, temporal change of domain is obtained by using piezoresponse force microscopy and a stretched exponential decay mechanism is applied. In the (111)-PTO thin films, dipole frustration is induced because of poling and redistribution of dipoles occurred to release dipole frustration. During relaxation, dipole-dipole interaction should be addressed and it gives a deep insight to understand fundamental relaxation mechanism of ferroelectric thin films.