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Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
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Resolving atomic-scale stick-slip and sub-moiré frictional modulation in twisted bilayers with variable tip sizes.
Sweta Das1, Niharika Mohapatra1, Hemant Kumar1
1School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha 752050, India.
Summary
Friction in twisted molybdenum disulfide (MoS2) bilayers depends on tip size. Smaller tips reveal lattice-scale stick-slip, while larger tips show moiré-dominated friction, resolving experimental discrepancies in 2D materials.
Area of Science:
- Materials Science
- Nanotechnology
- Tribology
Background:
- Nanoscale friction in twisted MoS2 bilayers is influenced by tip-sample interactions and moiré potential.
- Experimental friction force microscopy shows discrepancies related to tip size, obscuring lattice-scale dynamics.
Purpose of the Study:
- To investigate the effect of tip size on nanoscale friction in MoS2 bilayers using molecular dynamics simulations.
- To resolve discrepancies in experimental measurements and understand tip-size effects on frictional behavior.
Main Methods:
- Molecular dynamics simulations were used to model MoS2 bilayers with varying tip sizes (0.5-3 nm).
- Analysis focused on frictional behavior, amplitude modulation, and interlayer displacement.
Main Results:
- A transition in frictional behavior was observed with increasing tip size, from lattice-scale stick-slip to moiré-dominated periodicity.
- Larger tips averaged atomic oscillations, shifting friction maxima due to enhanced interlayer displacement.
- Lattice-scale periodicity and sub-moiré variations in friction were identified.
Conclusions:
- Tip size significantly impacts nanoscale friction measurements in MoS2 bilayers.
- High-resolution probes (<2 nm) are recommended for accurate frictional mapping.
- Findings inform the design of moiré-based systems with tunable tribological properties.
