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(CBNO) is demonstrated using non-resonant twisted ultra-violet (UV) light (375 nm, 800 THz). Combining in situ X-ray Bragg coherent diffractive imaging (BCDI), twisted optical Raman spectroscopy, and density functional theory (DFT), three-dimensional (3D) ionic displacements, strain fields, and polarization changes are resolved in single crystals. Operando measurements reveal light-induced strain hysteresis under twisted light-a hallmark of nonlinear, history-dependent ferroelastic switching driven by OAM. Discrete, irreversible domain transitions emerge as the topological charge ℓ is cycled, stabilizing non-trivial domain textures including vortex-antivortex pairs, Bloch/anti-Bloch points, and merons. These persist after OAM removal, indicating a memory effect. Competing mechanisms are discussed, including multiphoton absorption, strain-mediated polarization switching, and defect-wall interactions. The findings establish structured light as a tool for deterministic, reversible control of ferroic states, enabling optically reconfigurable non-volatile devices.
Nazirkar et al. (Fri,) studied this question.