Resonance Raman spectroscopy of twisted interfaces in turbostratic multilayer graphene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Turbostratic multilayer graphene features numerous interfaces with varying twist angles.
• Understanding these twist angles is key to controlling graphene's electronic and optical properties.

Purpose of the Study:

• To systematically investigate the impact of laser excitation energy on Raman modes in turbostratic graphene.
• To develop a method for characterizing a wide range of twist angles within the same sample.

Main Methods:

• Utilizing four distinct laser excitation energies to probe Raman spectra.
• Analyzing rotational (R-modes) and D-like modes, which are sensitive to superlattice potentials.
• Investigating the dispersion and intensity of Raman modes with varying laser wavelengths.

Main Results:

• Successfully identified twist angles from 5° to 30° at the same sample location.
• Observed R-modes and D-like modes, correlating their dispersion and intensity with superlattice effects.
• Determined an anomalous broadening factor for the resonance window, suggesting unique electronic interactions.

Conclusions:

• The combination of multiple laser energies is essential for comprehensive twist angle analysis in turbostratic graphene.
• Raman spectroscopy provides a powerful tool for probing superlattice effects and electronic structures in complex graphene systems.
• The observed phenomena offer insights into the fundamental properties of twisted multilayer graphene.