Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 88: Electronic Structure Theory: New Concepts and Developments in Density Functional Theory and Beyond - VI

O 88.9: Vortrag

Donnerstag, 23. März 2017, 12:30–12:45, GER 38

Ab-initio study of the Raman spectra of strained graphene — •Albin Hertrich, Caterina Cocchi, Pasquale Pavone, and Claudia Draxl — Department of Physics, Humboldt-Universität zu Berlin, Germany

Raman spectroscopy is an important non-destructive method for characterizing graphene-based materials. The main features of Raman spectra of pristine graphene are the first-order G-band at ≈ 1580 cm−1 and the dispersive second-order 2D-band at ≈ 2700 cm−1. In this work, we perform a systematic analysis on the effect of strain on both bands. All calculations are done using the full-potential all-electron code exciting [1]. Phonon properties are computed within the frozen-phonon approximation, the frequency-dependent dielectric tensor within the random-phase approximation. Raman-scattering intensities are calculated from vibrational matrix elements and derivatives of the dielectric tensor with respect to the phonon normal coordinates [2]. Under biaxial strain both Raman bands are shifted, while uniaxial strain leads to a splitting of the G-band by lifting the degeneracy of the optical in-plane Γ-point phonons. Further, we explore the effect of different types of inhomogeneous strain on the optical phonon frequencies and Raman-scattering intensities.

[1] A. Gulans et al., J. Phys.: Condens. Matter 26, 363202 (2014).

[2] C. Ambrosch-Draxl et al., Phys. Rev. B 65, 064501 (2002).

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