Atomic domino effect drives phase changes in two-dimensional crystal MoTe2

On July 6, 2026, a research team from the Chinese Academy of Sciences revealed a groundbreaking discovery regarding phase transformations in monolayer molybdenum telluride (MoTe2). Led by Profs. Chen Xingqiu and Sun Yan, along with Prof. Niu Haiyang from Northwestern Polytechnical University, the findings were published in the Proceedings of the National Academy of Sciences on June 29, 2026. This study identifies a novel mechanism for phase transformation that contrasts sharply with traditional models.

Understanding Phase Transformations in 2D Materials

Phase transformations are critical phenomena where materials change their crystal structures, resulting in significant alterations in their properties. In two-dimensional systems, these transformations are particularly interesting due to the unique behaviors that arise from reduced dimensionality. The conventional understanding of phase changes in transition metal dichalcogenides, such as MoTe2, has primarily centered around the martensitic model, which suggests that atoms shift together through concerted displacements.

However, this traditional model failed to account for experimental observations indicating that transformations could occur under much lower energy conditions than predicted. The research team utilized deep learning potential-accelerated molecular dynamics simulations to explore the phase transformation from the semiconducting 1H phase to the semimetallic 1T' phase in MoTe2. Their simulations revealed a surprising one-dimensional domino-like chain reaction as the actual mechanism.

New Insights into the Domino-like Phase Transformation

The newly identified domino-like mechanism involves tellurium atoms sequentially hopping along a specific crystallographic direction. This process triggers a structural rearrangement characterized by Peierls distortion and local topological changes. Importantly, this pathway presents a substantially lower energy barrier compared to the martensitic shear route, thus facilitating phase changes that were previously thought to require higher energy inputs.

As the transformation progresses, it creates a free-energy landscape marked by multiple metastable states, diverging from the classical nucleation-and-growth scenario. This new understanding opens avenues for controlling phase transformations in two-dimensional materials, potentially leading to advancements in programmable electronic and photonic devices.

Implications for Future Technologies

The implications of this research extend beyond theoretical interest. The study elucidates the kinetic origins of both single-domain and multi-domain morphologies observed in simulations with varying cell sizes. The researchers propose that by manipulating these kinetic characteristics, it is possible to achieve reversible switching between single-domain and multi-domain configurations.

• Enhanced second-order nonlinear optical responses
• Light-induced shift current responses increased from approximately 70 μA/V² to about 470 μA/V²

This capability for rapid modulation of electronic states could significantly impact the development of next-generation materials for electronic and optoelectronic applications.

In summary, this work not only advances the understanding of phase transformation mechanisms in two-dimensional materials but also establishes a new paradigm for phase engineering in low-dimensional systems, paving the way for innovative technologies.