Interlayer Friction and Superlubricity in Single-Crystalline Contact Enabled by Two-Dimensional Flake-Wrapped Atomic...

Area of Science:

• Materials Science
• Nanotechnology
• Tribology

Background:

• Interlayer friction in 2D materials and heterostructures is crucial for understanding interlayer couplings and superlubricity.
• Directly measuring interlayer friction between well-defined 2D layers remains a significant experimental challenge.

Purpose of the Study:

• To develop a novel method for fabricating 2D flake-wrapped atomic force microscopy (AFM) tips.
• To directly measure interlayer friction between 2D flakes in single-crystalline contact.
• To investigate the physics of interlayer couplings and superlubricity in various 2D materials.

Main Methods:

• Thermally assisted mechanical exfoliation and transfer technique to create 2D flake-wrapped AFM tips.
• Direct measurement of interlayer friction using AFM.
• Analysis of rotation angle dependence and lateral force mapping.

Main Results:

• Achieved superlubricity with a friction coefficient as low as 10⁻⁴ between different 2D flakes and layered bulk materials.
• Observed rotation angle dependence of superlubricity for graphite, but not for graphite/h-BN due to lattice mismatch.
• Generated atomic-resolution lateral force maps of ReS₂ layers, revealing hexagonal patterns consistent with theoretical simulations.

Conclusions:

• The developed tribological system provides an effective experimental platform for studying interlayer couplings and friction in 2D materials.
• The findings offer new insights into the fundamental physics governing friction and superlubricity at the 2D material interfaces.
• This method enables precise characterization of friction at the nanoscale for layered materials.