Dislocation-induced modulation of polarization switching in bulk ferroelectric perovskites

Dislocations in perovskites are believed to disrupt their ferroelectric properties. In this study, a novel molecular dynamics approach utilizing a modified embedded-atom method with charge equilibration interatomic potential is employed to provide qualitative new insights into how dislocations in the bulk can modulate the ferroelectric behavior of perovskites. Results show that stress gradients induced by various dislocation configurations/densities influence the polarization distribution pattern and the domain switching process. This modulation affects the shape of the hysteresis loop. The dynamics of the intrinsic charge-lattice coupling mechanism reveal that changes in polarization patterns are more pronounced in regions under larger compressive or tensile stress. Specific stress thresholds are identified that mark significant changes in polarization behavior under different loading conditions, offering a significant step towards understanding how the heterogeneous stress/strain state of a material influences its ferroelectric properties. Additionally, we qualitatively uncovered the effect of dislocation density on the energy characteristics, offering material design guidelines for specific electronic applications. Lower dislocation densities widen the hysteresis response and enhance the polarization properties, desirable for random-access memory applications, that require long-term data preservation. In contrast, higher dislocation densities result in narrower hysteresis loops and sharper switching responses, optimizing the conditions for high-speed computing and power-sensitive logic devices.