Continuous Switching of Ferroelectric Domain via Blister-Induced Flexoelectricity in CuInP₂S₆

Flexoelectricity induced by scanning probe offers a promising, voltage-free mechanical approach for polarization switching in ultrathin ferroelectrics, circumventing issues such as leakage currents and dielectric breakdown. However, achieving mechanically reversible polarization switching by scanning probe remains challenging, primarily limited by the unidirectional tip-based loading and the clamping effect of the substrate. In this work, a controllable blister-based mechanical loading method is developed that enables localized out-of-plane deformation of suspended ferroelectric CuInP₂S₆ (CIPS) membranes. Phase-field simulation reveals that the blister-induced bulging deformation generates distinguishable flexoelectric fields between the central suspended region and the surrounding supported area. These opposite flexoelectric fields drive polarizations in opposite directions, as confirmed by experimental observations of reversed domains. Furthermore, bidirectional and reversible ferroelectric polarization switching within the suspended membrane is achieved by dynamically tuning the pressure differential. This study presents a novel strategy for domain engineering for ultrathin ferroelectrics, paving the way for voltage-free control in future electromechanical microelectronic devices.