Spatial Coupling of Ferroelectric Domain Walls and Crystallographic Defects in the PbTiO3 Films

Revealing interactions between defects and domain walls is important for understanding the ferroelectric and piezoelectric behaviors of a ferroelectric film, especially when considering the trend of device downscaling. By means of aberration-corrected transmission electron microscopy, domain patterns resulting from the interactions between 90 degrees/180 degrees ferroelectric domain walls and dislocations in the PbTiO3 thin films grown on SrTiO3 are systematically studied. It is found that the coupling of 90 degrees and 180 degrees domain walls with dislocations may induce the formation of 90 degrees charged domain walls and some other novel metastable domain configurations. Such domain patterns are observed to relax with 180 degrees domain walls annihilation and the reversal of polarization directions of a-and c-domain. The configurations of both dislocations and stacking faults may lead to a dramatic change of the domain patterns. Unusual dislocation strain field is identified for a dislocation with the burgers vector 45 degrees apart from a 90 degrees domain wall. These results provide new insights into the defect and domain wall interactions which are of critical importance for the development of nanoscale devices.