Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 78: Frontiers of Electronic Structure Theory: Many-Body Effects on the Nano-Scale V

O 78.4: Talk

Thursday, March 19, 2015, 11:30–11:45, MA 004

Plasmon and exciton dispersion in two dimensions — •Pier Luigi Cudazzo — LSI Ecole Polytechnique and ETSF, Palaiseau, France

Understanding the electronic properties of 2D materials requires the investigation of their elementary excitations that dictate their optical and transport properties. Using state-of-the-art Green's function many body approach we present a first principle study of the collective excitations (namely excitons and plasmons) in 2D materials. In particular from the evaluation of the dielectric function we investigated the exciton dispersion in graphane and hBN and the plasmon dispersion in metallic TMDs[1-3]. From our results we provide an exact analytic form of the two-dimensional screened potential. In contrast to 3D systems where the macroscopic screening can be described by a static dielectric constant in 2D systems the macroscopic screening is non local (q-dependent) showing a logarithmic divergence for small distances and reaching the unscreened Coulomb potential for large distances[4].

[1] P. Cudazzo, et. al. New J. Phys. 15 125005 (2013). [2] P. Cudazzo, et. al. (in preparation) [3] P. Cudazzo, et. al. Phys. Rev. Lett. 104 226804 (2010). [4] P. Cudazzo, et. al. Phys. Rev. B 84 085406 (2011).