Temperature and strain effects on polarization switching in HfO2 ferroelectrics based on first-principles study

Abstract

HfO2-based ferroelectric materials have attracted intense interest due to their appealing potential in next-generation nonvolatile memories. However, the polarization switching mechanism, which is susceptible to the external factors, remains poorly understood. Among the factors, the temperature and epitaxial strain play important roles on the dynamic polarization switching of HfO2 ferroelectrics. In this work, we systematically investigate the effects of temperature and in-plane strain on the polarization switching behavior of HfO2 by combining the density functional theory and ab initio molecular dynamics. It is found that increasing temperature reduces both the spontaneous polarization and the switching electric fields of HfO2 no matter for the switching pathways with oxygen atoms passing through the Hf atomic planes (T-pathway) or not (N-pathway). Compressive strain decreases the energy barrier and switching electric field of the T-pathway polarization switching, whereas tensile strain substantially reduces those of the N-pathway switching. These findings provide atomistic insights for the understanding and rational tailoring of the polarization switching characteristics of HfO2-based ferroelectrics.