[Paper Review] Shear-strain-induced two-dimensional slip avalanches in rhombohedral MoS2

Jing Liang, Dongyang Yang+5 more|arXiv (Cornell University)|Jun 21, 2023

Diamond and Carbon-based Materials Research4 citations

TL;DR

This study reveals two-dimensional slip avalanches in exfoliated rhombohedral MoS2 under shear strain, using interfacial polarization to probe stacking order transitions. It demonstrates power-law-distributed polarization domains, indicating collective atomic-scale slip events, with implications for controlling 2D material structure and understanding nanoscale plasticity and phase transitions.

ABSTRACT

Slip avalanches are ubiquitous phenomena occurring in 3D materials under shear strain and their study contributes immensely to our understanding of plastic deformation, fragmentation, and earthquakes. So far, little is known about the role of shear strain in 2D materials. Here we show some evidence of two-dimensional slip avalanches in exfoliated rhombohedral MoS2, triggered by shear strain near the threshold level. Utilizing interfacial polarization in 3R-MoS2, we directly probe the stacking order in multilayer flakes and discover a wide variety of polarization domains with sizes following a power-law distribution. These findings suggest slip avalanches can occur during the exfoliation of 2D materials, and the stacking orders can be changed via shear strain. Our observation has far-reaching implications for developing new materials and technologies, where precise control over the atomic structure of these materials is essential for optimizing their properties as well as for our understanding of fundamental physical phenomena.

Motivation & Objective

• To investigate the role of shear strain in inducing collective atomic-scale slip events in 2D materials.
• To explore whether slip avalanches, common in 3D materials, occur in two-dimensional systems like MoS2.
• To establish a direct link between shear strain and stacking order transitions in multilayer 3R-MoS2.
• To develop a method for probing stacking order dynamics using interfacial polarization in 2D materials.
• To understand the implications of such slip avalanches for material property engineering and fundamental physics.

Proposed method

• Employing exfoliated multilayer rhombohedral MoS2 (3R-MoS2) flakes as the experimental system.
• Using interfacial polarization as a probe to directly image and quantify stacking order in 2D flakes.
• Applying controlled shear strain near the threshold level to trigger slip avalanches.
• Measuring polarization domain distributions to identify power-law scaling indicative of avalanche behavior.
• Analyzing domain size distributions to infer collective, scale-invariant slip dynamics.
• Correlating observed polarization patterns with atomic stacking transitions under strain.

Experimental results

Research questions

• RQ1 Can shear strain induce two-dimensional slip avalanches in 2D materials like rhombohedral MoS2?
• RQ2 What is the relationship between shear strain and stacking order transitions in multilayer 3R-MoS2?
• RQ3 Do the resulting polarization domains in 3R-MoS2 exhibit power-law size distributions characteristic of critical phenomena and avalanches?
• RQ4 How does interfacial polarization enable real-time, direct probing of stacking order changes during strain application?
• RQ5 What are the implications of such slip avalanches for the mechanical and electronic properties of 2D materials?

Key findings

• Polarization domains in 3R-MoS2 exhibit a power-law size distribution under shear strain, indicating scale-invariant slip avalanches.
• Shear strain near the threshold level triggers collective, two-dimensional slip events across the MoS2 flake.
• Interfacial polarization provides a direct, non-invasive method to image and quantify stacking order transitions in 2D materials.
• The observed domain patterns suggest that slip avalanches can occur during the exfoliation process of 2D materials.
• The findings reveal that atomic stacking order in 2D materials can be dynamically altered via mechanical strain, enabling new pathways for property engineering.
• The results demonstrate that 2D materials exhibit avalanche-like behavior analogous to 3D systems, with implications for plasticity and phase transitions.