The asymmetric butterfly curve had

The asymmetric butterfly curve had two stable strain states at zero electric field. Thus, the strain
memory effect was realized as the difference between the two stable strain states. An XRD analysis
was carried out to verify the contribution of the non-180◦ domain reorientation to the strain memory
effect. The non-180◦ domain reorientation was determined as the intensity ratio of the (002)
to the (200) peak. The strain memory determined from macroscopic strain measurements had a
linear relationship to the non-180◦ domain volume fraction. This result indicated the origin of the
strain memory to be the non-180◦ domain reorientation.