Breaking the synchrony of sliding ferroelectricity and sliding energy barrier

Abstract Two-dimensional (2D) materials demonstrate exceptional sliding ferroelectricity, owing to their facilitated interface charge transfer and controllable interlayer sliding. The development of high-performance sliding ferroelectric materials necessitates substantial sliding-induced polarization alongside minimal energy barriers for fatigue resistance. However, since both the sliding-induced ferroelectric out-of-plane polarization (OOP) and energy barriers are governed by interfacial charge transfer, these two critical parameters exhibit intrinsic coupling characteristics. The absence of the underlying mechanism, compounded by the lack of sliding ferroelectricity descriptor, fundamentally impedes the rational design of high-performance sliding ferroelectrics. In this work, we find the interfacial differential charge (IDC) transfer is an intrinsic parameter to link the sliding ferroelectricity and sliding energy barrier. Tracking all of the reported sliding ferroelectric materials, the sliding-induced OOP is found to be proportional to the dipole moments of asymmetric IDC distributions, while the sliding energy barrier is proportional to the absolute difference of IDC transfer. Leveraging high-throughput screening, 45 sliding ferroelectric candidates over 2000 homobilayer junctions are identified with superior sliding ferroelectric performance than MoS2. Then, a sliding ferroelectricity descriptor is proposed, that is OOP to the ratio between sliding energy barrier and cohesion energy. We further show that moiré superlattices can suppress net IDC transfer, enabling almost zero sliding energy barrier, but OOP switching during sliding. These insights elucidate the atomic origins of sliding ferroelectricity and establish a predictive framework for designing energy-efficient, fatigue-resistant ferroelectric devices.