Strain-dependent Splitting of Double Resonance Raman Scattering Band in Graphene

TL;DR

This study investigates how uniaxial strain affects the Raman 2D band in graphene, revealing strain-induced splitting and shifts due to changes in electronic and phononic properties, combining experimental and theoretical approaches.

Contribution

It provides a detailed understanding of the strain-dependent splitting of the Raman 2D band in graphene through combined polarized Raman measurements and first-principles calculations, clarifying the dominant scattering pathway.

Findings

Raman 2D band splits into two peaks under uniaxial strain.

The shifts and splitting depend on strain direction and magnitude.

Quantitative agreement between experiment and theory identifies the main scattering path.

Abstract

Under homogeneous uniaxial strains, the Raman 2D band of graphene involving two-phonon double-resonance scattering processes splits into two peaks and they altogether redshift strongly depending on the direction and magnitude of the strain. Through polarized micro- Raman measurements and first-principles calculations, the effects are shown to originate from significant changes in resonant conditions owing to both the distorted Dirac cones and anisotropic modifications of phonon dispersion under uniaxial strains. Quantitative agreements between the calculation and experiment enable us to determine the dominant double- resonance Raman scattering path, thereby answering a fundamental question concerning this key experimental analyzing tool for graphitic systems.