Ferroelectricity in the complementary metal-oxide semiconductor
(CMOS)-compatible hafnia (HfO2​) is crucial for the fabrication of
high-integration nonvolatile memory devices. However, the capture of
ferroelectricity in HfO2​ requires the stabilization of
thermodynamically-metastable orthorhombic or rhombohedral phases, which entails
the introduction of defects (e.g., dopants and vacancies) and pays the price of
crystal imperfections, causing unpleasant wake-up and fatigue effects. Here, we
report a theoretical strategy on the realization of robust ferroelectricity in
HfO2​-based ferroelectrics by designing a series of epitaxial
(HfO2​)1​/(CeO2​)1​ superlattices. The advantages of the designated
ferroelectric superlattices are defects free, and most importantly, on the base
of the thermodynamically stable monoclinic phase of HfO2​. Consequently, this
allows the creation of superior ferroelectric properties with an electric
polarization >25 μC/cm2 and an ultralow polarization-switching energy
barrier at ∼2.5 meV/atom. Our work may open an entirely new route towards
the fabrication of high-performance HfO2​ based ferroelectric devices