Fluorite ferroelectrics such as hafnia defy our understanding of ferroelectricity, even with regard to the intrinsic properties of ideal crystals. Here, we focus on a critical puzzle: the sign of the electric polarization. Using first-principles simulations, we show that a polar hafnia layer with a fixed atomic configuration can give rise to depolarizing fields of either positive or negative sign, depending on the environment. This implies that the polarization of bulk hafnia is not well defined, thus being extrinsic in nature. We explain this result and discuss its relevance to other ferroelectric families.

Close

PrevNext

View figure in article

• Electric polarization
• Ferroelectricity
• Interfaces
• Density functional theory