Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 77: 2D Materials Beyond Graphene IV
O 77.7: Vortrag
Mittwoch, 22. März 2017, 16:45–17:00, WIL A317
Plasmonic Superconductivity in Layered Materials — Malte Rösner1,2, Roelof G. Groenewald1, Gunnar Schönhoff2, Jan Berges2, Stephan Haas1, and •Tim O. Wehling2 — 1Department of Physics and Astronomy, University of Southern California, USA — 2Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, Germany
Due to a lack of screening in two dimensions the Coulomb interaction is generally enhanced and consequently plays a major role to understand many-body effects within layered materials. In the field of superconductivity it is usually introduced as an approximate, static, and adjustable parameter µ* which describes only effectively the Coulomb repulsion which is therefore responsible for reduced transition temperatures.
Here, we overcome this inadequate handling and present an ab initio based material-realistic Coulomb description for doped single layers of MoS2 which captures simultaneously material-intrinsic, substrate, and dynamical screening processes. Using this model we can reliably describe the resulting plasmonic excitations including both, their coupling to the electrons and their dependence on the environmental screening and doping level. Utilizing Eliashberg theory we show that the low-energy plasmonic modes originating from the dynamically screened Coulomb repulsion can actually lead to an effective Coulomb attraction and thus to an enhanced transition temperature (Tc). Furthermore, we find an optimal ratio between the substrate screening and the electron doping which maximizes Tc of the induced plasmonic superconducting state.