Atomical‐Rippled‐Nanodomains Stabilized Large Polarization in BiSmCo ₂ O ₆ Double‐Perovskite Films

Double-perovskite ferroelectrics have attracted increasing attention due to their highly tunable structures, multifunctional coupling effects, and potential applications in next-generation nonvolatile ferroelectric semiconductor devices. Here, an atomical-rippled-nanodomains (ARNs) are introduced to BiCoO₃ and SmCoO₃ solid solution double-perovskite film due to its ferroelectric single-domain coupling. By engineering triaxial tensile strain, the ferroelectric ARNs are robustly formed in BiSmCo₂O₆ double-perovskite films, leading to a large ferroelectric polarization (≈23.1 µC cm^-2) and ultra-enduring ferroelectric fatigue resistance exceeding 10¹² cycles without degradation. These results represent a significant enhancement in the performance boundaries of orthorhombic type-II multiferroics. The ferroelectric switching dynamics reveal the intrinsic correlation between the continuous switchable ARNs and the outstanding ferroelectric behavior. These findings underscore the effectiveness of nanodomain-coupling strategy for realizing high-performance ferroelectrics and offer a promising pathway toward designing correlated oxide-based ferroelectric semiconductor devices with exotic functionalities.