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TT: Fachverband Tiefe Temperaturen

TT 80: 2D Materials Beyond Graphene: TMDCs, Silicene and Relatives (organized by O)

TT 80.2: Vortrag

Mittwoch, 18. März 2015, 15:15–15:30, MA 005

From optics to superconductivity: Many body effects in transition metal dichalcogenides — Malte Rösner^{1, 2}, Gunnar Schönhoff^{1, 2}, Alexander Steinhoff¹, Frank Jahnke¹, Christopher Gies¹, Stephan Haas³, and •Tim Wehling^1,2 — 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.