Creating Ferroelectricity in Monoclinic (HfO2)1/(CeO

Ferroelectricity in CMOS-compatible hafnia (${\mathrm{HfO}}_{2}$) is crucial for the fabrication of high-integration nonvolatile memory devices. However, the capture of ferroelectricity in ${\mathrm{HfO}}_{2}$ 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 ${\mathrm{HfO}}_{2}$-based ferroelectrics by designing a series of epitaxial $({\mathrm{HfO}}_{2}{)}_{1}/({\mathrm{CeO}}_{2}{)}_{1}$ superlattices. The designed ferroelectric superlattices are defects free, and most importantly, on the base of the thermodynamically stable monoclinic phase of ${\mathrm{HfO}}_{2}$. Consequently, this allows the creation of superior ferroelectric properties with an electric polarization $>25\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{C}/{\mathrm{cm}}^{2}$ and an ultralow polarization-switching energy barrier at $\ensuremath{\sim}2.5\text{ }\text{ }\mathrm{meV}/\mathrm{atom}$. Our work may open an avenue toward the fabrication of high-performance ${\mathrm{HfO}}_{2}$-based ferroelectric devices.