Laser-Driven Structural Transformation from a Bulk Crystal to a Layered Material.

Laser-induced phase transitions offer pathways of phase transitions that are inaccessible by conventional stimuli. In this Letter, we conduct ab initio simulations to numerically demonstrate a novel laser-induced structural transformation: converting a bulk crystal into a layered van der Waals material using intense light pulses. The transition is driven by a nonlinear phononic mechanism, where selectively exciting polar and antipolar phonon modes with polarized terahertz light breaks targeted interlayer bonds while preserving intralayer ones. We identify that strong anisotropy in bond sensitivity-where interlayer bonds are significantly more susceptible to excitation than intralayer bonds-is the critical prerequisite. Our findings pave the way for on-demand transformations from bulk to 2D materials, facilitate the design of advanced phase-change devices, and suggest a potential optical exfoliation method to expand the range of exfoliable 2D materials.