Identifying Ferroelectric Switching Pathways in HfO2: First Principles Calculations under Electric Fields

The switching dynamics in the ferroelectric HfO2 is investigated using first principles calculations. Several possible switching pathways were first identified based on symmetry aspects of ferroelectricity. From calculations of the atomic response to finite electric fields however we find that in the two most likely pathways the inert oxygen atoms also play a role, in contrast to what had been reported previously based only on kinetic considerations. The hysteresis curves and coercive fields calculated along the pathways are compared with the intrinsic coercive field extracted from previous experimental data. The surface effect is discussed as a potential source of the mismatch between calculations and experimental data.