First-principles study of 180° domain walls in BaTiO3: Mixed Bloch-Neel-Ising character

The 180 degrees ferroelectric domain walls (FDWs) have long been regarded as purely Ising type in ferroelectrics, but recent theoretical works suggested that they can also have Neel- and/or Bloch-like rotations. Using a combination of first-principles calculations with phase-field simulations, we studied the 180 degrees FDWs on different crystallographic planes in prototypical ferroelectric perovskite BaTiO3. The polarization profiles of 180 degrees FDWs on (100) and (410) planes revealed that the (100)- and (410)-FDWs both exhibit Neel-like character besides their intrinsic Ising character, while the (410)-FDW also simultaneously shows a Bloch-like oblique of similar to 6 nm, as a consequence of the deviation of polarization gradient from the high symmetry direction. Due to the existence of the Neel-like component of polarization, 180 degrees FDWs in BaTiO3 exhibit a multilayer charge redistribution and thus may strongly trap charged defects.