Stacking-Dependent Interlayer Coupling in Trilayer MoS₂ with Broken Inversion Symmetry.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Stacking configuration in 2D materials dictates structural symmetry and interlayer interactions, influencing electronic properties.
• Few-layer graphene examples (ABA vs. ABC) highlight the tunability of electronic behavior based on stacking.
• Understanding stacking-dependent phenomena is crucial for advanced electronic device design.

Purpose of the Study:

• To investigate how different stacking configurations in few-layer molybdenum disulfide (MoS2) affect its electronic and vibrational properties.
• To correlate interlayer interactions with specific stacking arrangements using advanced spectroscopic techniques.
• To elucidate the role of spin-orbit coupling (SOC) and structural symmetry in layer-dependent properties.

Main Methods:

• Growth of few-layer MoS2 samples with controlled stacking (AA, AB, AAB, ABB, ABA, AAA) via chemical vapor deposition (CVD).
• Characterization using photoluminescence and Raman spectroscopy.
• Application of ultralow-frequency (ULF) Raman spectroscopy to probe interlayer vibrations.
• Ab initio calculations to model electronic properties and coupling mechanisms.

Main Results:

• Distinct photoluminescence and Raman spectral features were observed for MoS2 samples with varying stacking configurations.
• Ultralow-frequency Raman spectroscopy demonstrated a strong correlation between interlayer interaction evolution and layer-breathing mode (LBM) vibrations.
• Ab initio calculations confirmed that spin-orbit coupling (SOC) and interlayer coupling, influenced by structural symmetry, are key factors in layer-dependent properties.

Conclusions:

• The stacking configuration is a critical parameter for tuning the properties of few-layer MoS2.
• Interlayer coupling, particularly the layer-breathing mode, serves as a sensitive indicator of stacking arrangement.
• This research provides fundamental insights into the interplay of structure, spin-orbit coupling, and electronic properties, guiding future spintronics applications with MoS2.