Polarization switching of HfO2 ferroelectric in bulk and electrode/ferroelectric/electrode heterostructure

HfO₂-based ferroelectric films are of great potential for the application of non-volatile information storage. In this paper, to understand the polarization switching properties of ferroelectric HfO₂, the 180° polarization switching of HfO₂ film in the uniform polarization reversal and domain evolution are studied in both bulk form and Ni/HfO₂/Ni heterostructure based on the climbing image nudged elastic band (CI-NEB) simulation. It is found that the polarization reversal pathway with O atoms not shifting through the Hf-atomic planes has higher domain nucleation energy barrier due to the induced high energy domain wall (DW) but lower DW migration energy barrier, which is contrary to the pathway with O atoms shifting through the Hf-atomic planes. However, the interface effect of heterostructure considerably lower the energy barrier for the latter pathway in both uniform polarization reversal and DW migration. This indicates that both types of pathways may be possible and synergistically determine the polarization switching mechanism of HfO₂ ferroelectric.