Abstract
Atomistic and electronic structures of the 90° domain wall (DW) in PbTiO_3 are investigated using ab initio (first-principles) calculations based on the density-functional theory (DFT). At the domain wall, the magnitude of polarization decreases by 20% from that of bulk and the polarization direction rotates by 90 degrees. Furthermore, we have studied the domain switching which is an abrupt movement of the domain wall induced by shear stress. Our simulation demonstrates that the domain wall begins to move in the normal direction to the wall when the stress reaches at the critical value of 152MPa. During the domain switching, a covalent Pb-O bond at the center of DW breaks and another Pb-O bond is newly constrcuted.
