We investigated the atomistic and electronic structure of the 90° domain wall in $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ and the fundamental mechanism of domain switching induced by shear stress using first-principles density functional theory calculations within the local density approximation. Under strain-free condition, the magnitude of polarization at the center of the domain wall decreased by 20% from that of the bulk, and the direction rotated within the transition region of $1.3\mathrm{nm}$. Under strain, the applied shear deformation concentrated near the 90° domain wall, and the domain wall began to migrate in a direction perpendicular to itself after the stress reached the critical magnitude of $152\mathrm{MPa}$. The migration direction was governed by the shearing direction. During stress-induced domain switching, a Pb-O covalent bond at the center of the domain wall broke, and concurrently, another bond on the neighboring Pb-O site was formed with a large movement of the Pb atom. Thus, reconstruction of the Pb-O bond was associated with the domain switching.

• Received 16 January 2008

DOI:https://doi.org/10.1103/PhysRevB.77.094105