How Defects Freeze Ripples in 2D Materials

Two-dimensional (2D) materials exhibit nanoscale ripples that fundamentally influence their mechanical, electronic, and chemical properties. Introducing atomic defects is a common strategy to tailor these materials for specific applications, yet understanding the intricate relationship between ripple dynamics and defect characteristics remains challenging. Experimental techniques often lack the necessary resolution to capture the full temporal evolution of ripples across an entire membrane.

In this talk, I will present how machine-learning-driven simulations of graphene, the prototypical 2D material, allow us to probe the connection between ripples and different types of atomic defects. Specifically, we find that above a critical defect concentration, free-standing graphene sheets undergo a transition from freely propagating ripples to static buckling. Our computational approach resolves these dynamics at atomic resolution, revealing that this transition is governed by elastic interactions between defects. The strength of these interactions varies across defect types, and by quantifying their impact using structural and dynamic metrics, we establish a unifying framework for understanding the dynamic-to-static transition in 2D materials.

Our findings help reconcile puzzling experimental observations and open new avenues for designing 2D devices with precisely controlled rippling behaviour, potentially enabling novel applications in nanotechnology.