Huge mobility difference between the neutral and charged steps on 180° domain walls of PbTiO3 by first-principles calculations

Abstract

The microscopic mechanism of ferroelectric switching is the motion of domain walls, which is actually accomplished by the movement of tiny steps on the domain walls. Using first-principles calculations, the detailed polarization structures and the motion barriers of neutral and charged steps on 180° domain walls of prototypical ferroelectrics PbTiO3 are elaborately revealed in this study. While the Bloch components get weakened near all neutral steps, they become weakened/strengthened near the head-to-head/tail-to-tail charged steps. The neutral step possesses a lower formation energy but a higher migration barrier, indicating that the charged step could move faster. Based on these results, the possible motion picture of steps on one 180° domain wall of tetragonal ferroelectrics is proposed, which provides a better understanding of the mechanism of domain wall motion and may shed light on the future development of domain wall–based functional devices.