Robust In‐Plane Ferroelectricity in Ultrathin Epitaxial Aurivillius Films

Abstract

AbstractLayered ferroelectrics, often referred to as natural superlattices, exhibit functionalities beyond those of the classical ferroelectric perovskite compounds due to their highly anisotropic structure. Unfortunately, the layered architecture has been impeding their growth as single crystalline thin films, and thus their integration into oxide‐electronic devices. Here, fatigue‐free ferroelectric switching in epitaxial Bi5FeTi3O15 thin films is demonstrated. The achievement of twin‐free films with sub‐unit‐cell thickness precision on a lattice‐matching NdGaO3 orthorhombic substrate significantly enhances their uniaxial ferroelectric properties. In the ultrathin regime, such films exhibit in‐plane polarization with a periodic arrangement of ferroelectric domains, which, with uniaxial ferroelectric anisotropy, results in nominally charged domain walls. The uniaxial in‐plane ferroelectricity and remarkable endurance after 1010 switching cycles of Aurivillius thin films breaks new ground for alternative device paradigms that are less susceptible to limitations arising from the depolarizing‐field effects in the ultrathin regime.