Complex polarization ordering in PbTi03 nanowires: A first-principles computational study

Based on parameter-free density functional theory calculations, we demonstrate the possibility of non-rectilinear 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 A. We also report previously unknown phase transitions between the non-rectilinear 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.