Mohit Tanwani

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.

Antiferroelectric thin films can stabilize electrically written metastable polar states, but deterministic reset of these states after electrical writing remains challenging. Here, we demonstrate that localized mechanical force can deterministically erase an electrically written metastable polar state in epitaxial PbHfO ₃ thin films, driving the system back toward the antipolar antiferroelectric ground state. Electrical bias stabilizes a persistent metastable polar state, whereas once the polar state is established, tip‐applied mechanical force progressively suppresses both piezoresponse and surface‐potential contrast, consistent with force‐assisted relaxation of the polar state toward the antiferroelectric state. Time‐dependent measurements further reveal that the written ferroelectric state is intrinsically metastable and relaxes only slowly without external perturbation. Together, these results demonstrate a deterministic electromechanical write–erase paradigm, in which electric fields encode, and mechanical forces erase ferroic order. This work introduces a new modality for controlling competing ferroic phases and provides a foundation for mechanically reconfigurable nanoelectronic and logic devices based on antiferroelectrics.

Resistive switching in SrCoO _2.5 has been variably attributed to localized filamentary conduction and lattice‐scale oxygen redox; as a topotactic oxide capable of reversible oxygen exchange with minimal lattice disruption, it provides a model system to resolve this distinction, which is critical because the underlying mechanism governs switching stability, reproducibility, and device design. Here, we address this issue by directly comparing Au/SrCoO _2.5 /Nb‐SrTiO ₃ and SrRuO ₃ /SrCoO _2.5 /Nb‐SrTiO ₃ heterostructures using electrical transport measurements combined with operando bias‐dependent x‐ray absorption and hard x‐ray photoelectron spectroscopy, providing direct sensitivity to lattice‐oxygen‐driven redox processes. Devices with an oxygen‐inert Au electrode exhibit polarity‐restricted switching, whereas the oxygen‐active SrRuO ₃ electrode exhibits switching under both bias polarities within the investigated voltage window, consistent with participation of both interfaces in the bias‐induced redox response. Operando spectroscopy reveals electrode‐dependent modulation of the Co valence, while complementary structural and vibrational measurements show no macroscopic lattice change but clear local rearrangements of the oxygen coordination, indicating an interface‐controlled, spatially distributed redox mechanism. These results identify electrode oxygen‐exchange capability as an important parameter governing switching polarity and redox dynamics in topotactic transition‐metal oxides. The combined electrical and spectroscopic observations further support the contribution of a distributed redox mechanism to the switching process.