Ambient pressure-induced domain engineering in suspended CuInP2S6 membrane

The flexoelectric effect, which couples strain gradients to electric polarization, provides a promising method for ferroelectric domain engineering without the need for external electric fields. Applying localized forces to the surface of ferroelectric materials using scanning probes can generate strain gradients that induce domain reconfigurations. In this study, we present an alternative approach to flexoelectric-induced domain engineering in suspended two-dimensional CuInP2S6 (CIPS) membranes by varying the ambient pressure. By capping CIPS over cavity holes, internal air pressurization induces bulging, which results in unique encircled domain configurations governed by local strain gradients showing upward and downward polarizations at the center and the edge of the suspended membrane, respectively. Furthermore, this domain configuration can be bidirectionally modulated by varying the ambient pressure. We demonstrate reversible variations in domain size, driven by topographic changes that redistribute the strain gradient. Our findings demonstrate that ambient pressure can be used to engineer domains in suspended ferroelectric membranes, opening avenues for the development of emerging ferroelectric devices that are sensitive to ambient pressure.