Polarization Dynamics during Ferroic Oxide Thin Film Growth

Ferroelectric oxide films with a thickness of just a few atoms can now be grown with a precision matching that of semiconductors. This opens a whole world of functional device concepts and fascinating phenomena that would not occur in the expanded bulk crystal. The successful integration of ferroelectrics into nanoscale devices relies however on our ability to engineer deterministically polarization states in the application relevant ultrathin regime. Here I will show how nonlinear optics enables the in-situ investigation of the ferroelectric polarization during the thin film epitaxial growth. Beyond the unprecedented access to the emergence of ferroelectricity and domain formation during the epitaxial deposition, we investigate transient polarization states originating from the evolving charge-screening environment of the oxide thin film growth process. We show the impact of lattice chemistry, depolarizing field-related effects in-situ and identify routes towards the establishment of robust polarization states in the ultrathin regime. Our work provides new insights dealing with the physics of ultrathin ferroelectrics and further control of ferroelectric-based heterostructure.