Using molecular dynamics (MD) simulations based on first-principles effective Hamiltonian of bulk PbTiO3, we corroborate the occurrence of 90° ferroelectric domain structures showing that they arise as metastable states only in cooling simulations (as the temperature is lowered) and establish characteristic stability of 90° domain structure in PbTiO 3. In contrast, such domains do not manifest in similar simulations of bulk BaTiO3. Through a detailed analysis and comparison between PbTiO3 and BaTiO3, we find that the 90° domain structures are energetically favorable only in the former, and the origin of their stability lies in the polarization-strain coupling. Our analysis suggests that a possible origin of observed 90° domain structure in BaTiO3 has to be extrinsic, such as special boundary condition and/or defect-related inhomogeneities. We present transmission electron microscopy (TEM) images of 90° domain structure in PbTiO3, and compare the observed thickness of domain wall and size of domains with predictions of our simulations.
- First-principles effective Hamiltonian
- Phase transition
ASJC Scopus subject areas
- Physics and Astronomy(all)