Highly mobile vortex structures inside polar twin boundaries in SrTiO 3

Abstract

We present computer simulations of previously unknown polarization singularities (vortexes) inside polar SrTiO3 twin boundaries. Usually polarity in twin walls is ferri-electric, whereas vortex excitations lead to true ferroelectricity on a very local scale. As a result, in-plane electric fields can selectively stabilize one of the vortex polarization states and enhance the ability of the walls to move. This behavior can explain the well-known and uniquely high, mobility of twin boundaries in SrTiO3. For nanoscale ferroelectric memory devices, we envisage a precisely controllable device, where a desired domain wall pattern is manipulated by shifting the vortex position electrically. © 2014 Author(s).