Researchers at the Chinese Academy of Sciences and Northwestern Polytechnical University have identified a novel atomic-scale mechanism driving phase transitions in two-dimensional materials, challenging long-standing theoretical models. Published in the Proceedings of the National Academy of Sciences on June 29, the study details a one-dimensional domino-like chain reaction observed in monolayer molybdenum telluride, offering a new pathway for designing programmable electronic and photonic devices. For years, phase transitions in monolayer transition metal dichalcogenides were attributed to conventional martensitic processes, where large groups of atoms undergo concerted shear displacements. However, this classical model predicted energy barriers that significantly exceeded experimental observations, leaving the actual kinetic pathway unresolved. To bridge this theoretical gap, a collaborative team led by Professors Chen Xingqiu and Sun Yan from the Institute of Metal Research, alongside Professor Niu Haiyang, utilized deep learning potential-accelerated molecular dynamics simulations. Their computational analysis systematically mapped the transformation between the semiconducting 1H phase and the semimetallic 1T prime phase in monolayer MoTe2. Contrary to established theory, the simulations revealed that the phase transition proceeds via a sequential, one-dimensional hopping mechanism. Tellurium atoms migrate along a specific crystallographic axis, triggering localized structural rearrangements and Peierls distortion. This domino-like propagation bypasses the high-energy concerted shear required by the martensitic model, resulting in a substantially lower activation barrier and a free-energy landscape populated with multiple metastable states. The research team demonstrated that this kinetic pathway explains the emergence of both single-domain and multi-domain morphologies depending on system dimensions, providing a framework to deliberately control phase configurations. The practical implications of this discovery extend rapidly into device engineering. By leveraging the reversible switching between single-domain and multi-domain states, engineers can achieve rapid modulation of electronic properties. Furthermore, the transient intermediate structures generated during this transformation exhibit dramatically enhanced second-order nonlinear optical responses. Specifically, light-induced shift currents in the visible spectrum increase from approximately 70 μA/V2 to 470 μA/V2, indicating significant potential for advanced optoelectronic applications. This breakthrough redefines the understanding of phase kinetics in low-dimensional systems. By replacing the conventional martensitic paradigm with a domino-chain mechanism, the research establishes a new standard for phase engineering in two-dimensional crystals. The findings provide a robust theoretical foundation for developing next-generation programmable electronics, ultrafast optical switches, and adaptive quantum materials, marking a pivotal advancement in condensed matter physics and nanotechnology.