Quantitatively Predicting Angle-Resolved Polarized Raman Intensity of Anisotropic Layered Materials

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Angle-resolved polarized Raman (ARPR) spectroscopy reveals optical anisotropy and electron-phonon couplings in anisotropic layered materials (ALMs).
• ARPR responses in ALMs are complex, showing puzzling dependencies on flake thickness, excitation wavelength, and dielectric environment.
• Existing methods struggle to accurately predict ARPR intensity profiles for ALMs.

Purpose of the Study:

• To develop a predictive framework for ARPR intensity in ALM flakes.
• To introduce intrinsic Raman tensors (Rint) for accurate ARPR analysis.
• To account for factors like birefringence, linear dichroism, and multilayer interference in ARPR predictions.

Main Methods:

• Introduced intrinsic Raman tensors (Rint) and effective Raman tensors (Reff).
• Utilized experimentally determined complex refractive indexes for in-plane axes.
• Derived Reff elements to quantitatively predict ARPR intensity.
• Applied the framework to black phosphorus (BP) and four-layer Td-WTe2 flakes.

Main Results:

• Successfully predicted ARPR intensity profiles for ALM flakes of varying thickness.
• Demonstrated the intricate dependence of ARPR intensity on ALM thickness, dielectric substrates, and excitation wavelengths.
• The developed framework accurately accounts for optical phenomena like birefringence and multilayer interference.

Conclusions:

• The proposed framework enables accurate prediction of ARPR intensity for ALM flakes.
• This approach simplifies the understanding and prediction of ARPR responses in ALMs.
• The framework is extendable to various ALM thicknesses, from thin layers to the bulk limit.