Domain Wall Motion in Perovskite Ferroelectrics Studied by the Nudged Elastic Band Method

Abstract

Because of its unique physical properties, domain wall (DW) in ferroelectrics not only plays a key role in the electrical properties of ferroelectric film but also has shown tremendous prospect in the DW-based memory and logic devices. However, the motion mechanism of ferroelectric DW, which is of great significance for the application of ferroelectric films, has not been clearly understood. In this paper, the 180°DW motions in BaTiO 3 (BTO) and PbTiO 3 (PTO) were studied by using the nudged elastic band method based on the density functional theory. The evolutions of atomic structure, local polarization, and energy of the system for the DW motion process between the two adjacent equilibrium positions were systematically revealed. The DW migration across the oxygen vacancy was also simulated, and the corresponding potential well for the DW motion was obtained. It was also found that the DW motion barrier could be significantly influenced by the in-plane strain. The "activation field" deduced from the energy barrier of DW motion in the present calculation agrees with experimental values, which may provide a fundamental understanding of DW dynamics.

Defect‐Enhanced Polarization Switching in the Improper Ferroelectric LuFeO3

“…Another difference between proper ferroelectric perovskites such as PbTiO 3 and the improper ferroelectric h‐LFO is the interaction between oxygen vacancies and domain walls. While it is well established, both from experiments [ 35,36 ] and recent DFT studies, [ 37–44 ] that oxygen vacancies segregate to and pin ferroelectric domain walls, this is not the case for improper ferroelectrics like h‐LFO and YMnO 3 . [ 28,29 ] Following the extension of the coupling diagram for primary ferroic orders [ 45 ] to also include electrochemistry and stoichiometry, [ 46 ] our results demonstrate a strong and positive coupling between ferroelectricity and the chemical potential as a conjugate field.…”

Polarization Domain Dynamics of Barium Titanate Ultrathin Films Using Piezoresponse Force Microscopy.

“…7). The 10 nm film is Based on this result, the small difference in the activation field for our films can be expected due to the small difference in the strain observed in the films which would tend to make it more difficult to flip the dipole direction and have greater activation field 36 . As a result, our observations indicate that the constants in Eq.…”

Design of a multifunctional polar metal via first-principles high-throughput structure screening

“…To quantitatively calculate the energy barrier and identify a possible switching path for polar displacement, we perform the climbing image nudged elastic band (NEB) calculations 48 and use transition state theory 49 . Transition state theory has been widely used in understanding polarization switching in ferroelectric thin films 50,51 , as well as ferroelectric domain wall motion 52 . We choose "anti-parallel state" as the initial state and "parallel state" as the final state.…”