Complex polarization ordering in PbTiO3 nanowires: A first-principles computational study

Based on parameter-free density-functional-theory calculations, we demonstrate the possibility of nonrectilinear curling vortex electric dipole configurations in PbTiO3 nanowires. We predict that the critical size for the genesis of the vortex polarization instability (with an axial toroidal moment) is 16 angstrom. We also report previously unknown phase transitions between the nonrectilinear vortex and conventional rectilinear axial polarization configurations mediated by strain and surface terminations. The ability to switch reversibly between the vortex (clockwise/counterclockwise) and axial (positive/negative) polarization states may open up transformative technological possibilities.