Self-Restoration of a Wrinkled Hf_0.5Zr_0.5O₂ Ferroelectric Membrane

Ferroelectric oxides are generally prone to brittle deformation, which impedes their applicability in flexible devices. Using a damage-free peel-off process, we successfully synthesized wrinkled 10 nm thick membranes of zirconium-doped hafnium oxide Hf_0.5Zr_0.5O₂ (HZO). We studied their self-restoration dynamics via in situ scanning probe microscopy. Substantial deformations were induced as the tip descended by applying and sustaining a predefined static force at the crest of the wrinkled membrane. The membrane was fully restored to its original wrinkled state within a specific force range, with no observed damage after force removal. The membrane demonstrated self-restoration even after forces exceeding 100 nN, which completely collapsed the wrinkles, highlighting the exceptional flexibility of these freestanding HZO membranes─an uncommon property among functional oxides. Combining phase-field simulations, we observed the emergence of a region exhibiting continuous variation in polarization intensity within the strained area. The formation of this specific domain structure plays a pivotal role in the self-restoration behavior of the freestanding ferroelectric membranes. This self-restoration capability is essential for the long-term stability of flexible electronic devices, such as sensors, energy harvesters, and electronic skins.