Freestanding Membrane Enabled Multi‐Stimulus Ferroelectric Switching

ABSTRACT Substrate clamping constrains lattice deformation in epitaxial ferroelectrics, limiting the ability of weak non‐electrical stimuli to reconfigure polarization. Here, we show that releasing epitaxial PbTiO 3 into a freestanding membrane reshapes its switching landscape and enables polarization control through electrical, mechanical, and optical stimuli. Whereas substrate‐clamped PbTiO 3 remains stable under local mechanical loading up to 4000 nN and 405‐nm illumination, freestanding PbTiO 3 integrated on silicon exhibits force‐driven polarization reconfiguration from ∼2000 nN and pronounced light‐assisted modification of the written polar state. Mechanical release enhances the piezoresponse by ∼80%, reduces the switching voltage by ∼45%, and produces a strongly force‐tunable electromechanical response. Optical excitation further induces asymmetric switching and a positive hysteresis shift in the freestanding membrane, consistent with a photoinduced internal bias field. Kelvin probe force microscopy reveals photoinduced surface‐potential modulation in both clamped and freestanding geometries, yet corresponding polarization reconfiguration occurs only in the mechanically released membrane. This contrast demonstrates that photoinduced electrostatic perturbation alone is insufficient to drive polarization reconfiguration and that its effectiveness is governed by the mechanical boundary condition. Our findings establish mechanical release as a strategy for engineering the accessibility of ferroelectric switching pathways and enabling multi‐stimulus control in reconfigurable oxide membranes.