Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: 2D Materials I: Structure and Electronic Properties
O 32.8: Vortrag
Dienstag, 8. März 2016, 12:15–12:30, H24
Coulomb interaction in transition metal dichalcogenides: effects on many-body instabilities — •Gunnar Schönhoff1,2, Malte Rösner1,2, Stephan Haas3, and Tim Oliver Wehling1,2 — 1Institut für Theoretische Physik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany — 2Bremen Center for Computational Materials Science, Universität Bremen, Am Fallturm 1a, 28359 Bremen, Germany — 3Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA
We develop a material realistic, microscopic model to describe the Coulomb interaction in a TMDC monolayer, focussing on molybdenum disulfide under electron doping. Starting from ab initio Coulomb interaction for the undoped system, we calculate values for the screened matrix elements in real space and see how the interaction becomes more localized with doping. Additionally, we obtain the doping dependend electron-phonon matrix elements and observe a Charge Density Wave instability at high doping.
To quantify the influence of the Coulomb interaction on the superconducting phase, we calculate the Morel-Anderson coefficient µ*. In contrast to the frequent use of µ* as a fit parameter or a constant, this leads to a decrease of µ* with electron doping from 0.25 to 0.1. The influence of the Coulomb interaction turns out to be most important at the boundary between the metallic and the superconducting phase where it delays the phase transition. We argue that the character of the superconducting phase in MoS2 is phononic.