Universal intrinsic origin for ferroelectric domain wall motion*

The existence of domain walls in ferroelectric materials can have a profound influence on the properties of ferroelectrics [1]. We explored the dynamics of the 90$^\circ$ domain walls in PbTiO$_3$ with molecular dynamics simulations~[2] under a wide range of temperatures and electric fields. We found an intrinsic ``creep-depinning'' transition for the temperature- and field-dependence of the wall velocity, resulted from the nucleation-and-growth mechanism. By mapping non-180$^\circ$ domain walls to a 180$^\circ$ domain wall, we proposed an analytical model that is able to quantify the dynamics of all types of domain walls in various ferroelectrics, enabling rapid estimation of finite-temperature coercive fields with first-principles inputs. This work offers a unified picture for domain wall motion and an efficient framework for computational optimization of ferroelectrics. \\[4pt] [1] Seidel, J., J. Phys. Chem. Lett. {\bf3}, 2905 (2012). \\[0pt] [2] S. Liu, I. Grinberg, H. Takenaka, and A. M. Rappe, Phys. Rev. B {\bf 88}, 104102 (2013).