  Ferroelectric fluorite dioxides like hafnium (HfO2)-based materials are
considered to be one of the most potential candidates for nowadays large-scale
integrated-circuits (ICs). While zirconia (ZrO2)-based fluorites materials,
which has the same structure as HfO2 and more abundant resources and lower cost
of raw materials, is usually thought to be anti- or ferroelectric-like. Here we
reported a giant ferroelectric remnant polarization (Pr) amounted to 53
{\mu}C/cm2 in orthorhombic ZrO2 thin film at room temperature. This
ferroelectricity arises from an electric field induced anti-ferroelectric to
ferroelectric phase transition which is particularly noticeable at 77 K. Our
work reveals the intrinsic ferroelectricity in ZrO2 thin films and offers a new
pathway to understand the ferroelectricity origin in fluorite oxides.
