Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spectroscopy

Background:

• Two-dimensional (2D) layered materials possess unique properties tunable by their stacking arrangement.
• Characterizing these stacking patterns is crucial for unlocking their technological potential.
• Low-frequency (LF) Raman spectroscopy offers a rapid, non-destructive method for this analysis.

Purpose of the Study:

• To develop a generalized model for predicting LF Raman intensities based on interlayer stacking.
• To establish a unified nomenclature for stacking sequences in various 2D materials.
• To elucidate the fundamental mechanisms linking LF Raman response to stacking.

Main Methods:

• Proposal of a simple and generalized interlayer bond polarizability model.
• Application of the model to diverse 2D materials (graphene, MoS2, MoSe2, NbSe2, Bi2Se3, GaSe, h-BN, etc.).
• Development of a general strategy for unifying stacking nomenclature.

Main Results:

• The model accurately explains and predicts LF Raman intensities for complex stacking sequences and varying thicknesses.
• Demonstrated applicability across a broad range of 2D layered materials.
• Revealed the fundamental physics governing LF Raman sensitivity to stacking.

Conclusions:

• The proposed model provides a powerful tool for characterizing 2D material stacking.
• The unified nomenclature simplifies communication and comparison across different studies.
• This work offers generalizable rules for identifying stacking configurations using LF Raman spectroscopy.