Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 57: 2D Materials beyond Graphene: TMDCs, Slicene and Relatives
O 57.2: Talk
Wednesday, March 18, 2015, 15:15–15:30, MA 005
From optics to superconductivity: Many body effects in transition metal dichalcogenides — Malte Rösner1, 2, Gunnar Schönhoff1, 2, Alexander Steinhoff1, Frank Jahnke1, Christopher Gies1, Stephan Haas3, and •Tim Wehling1,2 — 1Institute for Theoretical Physics, University of Bremen, D-28359 Bremen, Germany — 2Bremen Center for Computational Material Sciences, University of Bremen, D-28359 Bremen, Germany — 3Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA
We discuss many body effects in MoS2 ranging from optical properties to the emergence superconductivity (SC) and charge density wave phases (CDW). Combining ab-initio theory and semiconductor Bloch equations we show that excited carriers cause a redshift of the excitonic ground-state absorption line, while higher excitonic lines disappear successively due to a huge Coulomb-induced band gap shrinkage of more than 500 meV and concomitant exciton binding-energy reductions. Upon strong charge doping, we observe a succession of semiconducting, metallic, SC, and CDW regimes. Both, the SC and the CDW instabilities trace back to a Kohn anomaly and related softening of Brillouin zone boundary phonons.