P2: Many-body instabilities in 2d materials

Supervision:Tim Wehling, Frank Jahnke

Motivation and state of the art: Several 2d materials combine strong Coulomb interactions with sizeable electron-phonon coupling, which leads to competing many-body instabilities including superconductivity (SC), charge density waves (CDW), exciton condensates and magnetism. The realization of these phases is highly sensitive to external stimuli and atomistic structural details, which offers unprecedented possibilities for materials engineering, e.g. in the context of layered heterostructures. An appropriate theoretical description requires an atomistic theory, which accounts for dynamic correlations, retarded local and non-local interactions, and remains to be established.

Aims and work plan: We will study how the 2-dimensionality of materials like MoS2, functionalized graphene or NbSe2 can be exploited to control many-body instabilities (SC, CDW and magnetism) by interfacing and doping and how characteristic temperatures can be enhanced. Methods to map realistic systems onto tractable many-body Hamiltonians will be advanced (projector and Wannier function methods) and their applicability will be extended towards vertical hetero-structures. Interfaces with many-body approaches such as Eliashberg theory, dynamical mean field theory (P3) and time-dependent non-equilibrium approaches (P4, P5, and P9) will be implemented and effects of electron plasmon coupling (P1) on many-body instabilities will be investigated.