Domain Switching and Interaction with Misfit Dislocation in Bismuth Ferrite thin films: Phase-Field Simulation

Previously, we reported a massively parallel 3D phase-field model that can simulate micron scale ferroelectric thin films with arbitrary electrical and mechanical boundary conditions [1,2]. Using this model, we explained a number of recent experimental results of domain switching on various surfaces of BiFeO3 [1,2]. Here, we study the inhomogeneous strain distribution and its impact on domain nucleation and switching in the multi-ferroic material BiFeO3. We calculate the inhomogeneous strain induced in a thin film BiFeO3 due to misfit dislocations. We simulate the domain growth mechanism in films with and without misfit dislocation. We find that a compressively strained region in the film due to dislocation act as nucleation center whereas a tensile strained region act as pinning centers for lateral electric fields on the (001) surface of BFO. Both domain growth and relaxation speed are considerably higher close to a compressively strained region when the domain propagates perpendicular to the dislocation. An opposite trend is observed for domains relaxing along the dislocation. Our calculated domain propagation velocities are in excellent agreement with recently reported experiments.\\[4pt] [1] J. Heron, M Trassin, K Ashraf, et al., PRL, 89, 153504 (2011)\\[0pt] [2] K Ashraf, S. Salahuddin JAP,111(10), 103904 (2012).\\[0pt] [3] K Ashraf, S. Salahuddin JAP,112, 074102 (2012).