Fig. 5: Polarisation changes under illumination simulated by DFT and domain wall properties at finite temperatures by MD simulations.
From: Subsecond optically controlled domain switching in freestanding ferroelectric BaTiO3 membrane
a Change of polarisation in clamped (compressive strain 2.2%) and relaxed BTO (tetragonal phase, no temperature, no clamping) by photo-excited carriers. Atomic structure of b BaO-centred (ground state) and c TiO2-centred (metastable state, energy barrier for wall motion) domain walls excerpted from the 16 × 1 × 1 unit cell used in DFT simulations. Arrows illustrate the local polarisation of each Ti-centred unit cell (arb. scale). d Polarisation profiles across BaO-centred (blue) and TiO2-centred (red) tetragonal 180° domain walls and their changes with the concentration of excited charges in e/f.u. (symbols). e Energy (∆E) landscape diagram of imprint ferroelectrics. The variation of energy landscape diagram of clamped (compressively strained) and freestanding (relaxed) films under dark and illumination. f Examples of polarisation profile 〈Pz〉x (average of Pz for all unit cells at the same x position) across a tetragonal BaO-centred 180° domain wall under 0.4% and 0.6% biaxial compressive strains found in finite temperature MD simulations. g Change of the critical field strength Ecr for domain wall motion under biaxial strains (negative/positive for compressive/tensile strain) found in MD simulations. The critical field strength of the unclamped material is shown by the star symbol.
