Hafnia-based ferroelectric materials have garnered considerable attention due to robust ferroelectricity in ultrathin films and excellent compatibility with silicon-based technology. Theoretical predictions of the polarization along 001 direction of ferroelectric HfO2 are 50 μC/cm2 and 70 μC/cm2, respectively, depending on the switching mechanism. However, most experimental observations of the intrinsic polarization are much lower than these predictions. Here, we report that an intrinsic remnant polarization up to 40 μC/cm2 is achieved in epitaxially grown (111)-oriented Hf0.5Zr0.5O2/Hf0.9La0.1O2 multilayer film, corresponding to 69.3 μC/cm2 along 001, approaching the theoretical limit. Structural analyses reveal a rhombohedral-distorted orthorhombic phase in the Hf0.5Zr0.5O2/Hf0.9La0.1O2 multilayers, stabilized by an in-plane compressive strain. Density functional theory calculations demonstrate that La doping in Hf0.5Zr0.5O2/Hf0.9La0.1O2 promotes an unconventional switching pathway and contributes to the high intrinsic polarization. These findings provide a compelling strategy for achieving high intrinsic polarization and establish a design paradigm for high-performance hafnia-based ferroelectric devices. HfO2-based ferroelectric materials are promising for non-volatile memory applications. Here, the authors demonstrate a highly enhanced ferroelectricity in Hf0.5Zr0.5O2/Hf0.9La0.1O2 multilayers, which approach the theoretical limit.
Shi et al. (Tue,) studied this question.