Project Details
Projekt
Non-equilibrium carrier dynamics and band structure of proximity-coupled graphene
Applicant
Professorin Dr. Isabella Gierz-Pehla
Subject Area
Experimental Condensed Matter Physics
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 449119662
Interfacing graphene with other 2D materials is a promising pathway to develop innovative synthetic quantum materials with custom-made electronic properties. To make this vision come true, the interdisciplinary research unit brings together experts in sample growth, characterization, electronic structure determination, correlation effects, microscopic and mesoscopic (magneto-)transport and ultrafast electron dynamics. The project specifically investigates ultrafast non-equilibrium carrier dynamics and transient band structures in different graphene-based heterostructures using time- and angle-resolved photoemission spectroscopy (trARPES), time-resolved photoemission electron microscopy (trPEEM) and time-resolved μARPES. We are particularly interested in (1) interfaces between graphene and 2D semiconductors where photoexcitation is followed by efficient ultrafast charge separation for applications in light harvesting and detection, (2) interfaces between graphene and topological insulators for efficient ultrafast spin injection into graphene, (3) interfaces between graphene and Mott insulators or heavy fermion compounds where the interplay between itinerant and localized electrons may result in different exotic ground states, (4) bilayer graphene with different twist angles, as well as (5) highly doped graphene on 2D Gadolinium, Ytterbium and Terbium with strong electron-electron and electron-phonon coupling. With support from density functional theory (DFT), density functional perturbation theory (DFPT) and dynamical mean field theory (DMFT) from project T2 we will seek answers to the following questions: (a) Can ultrafast PEEM and μARPES reveal the non-equilibrium carrier dynamics of individual domains in inhomogeneous samples where conventional trARPES fails? (b) Do we find evidence of ultrafast charge and spin transfer across the different interfaces? (c) How do Auger relaxation processes impact the non-equilibrium properties of the semiconducting carbon buffer layer? (d) Does the twist angle in bilayer graphene affect carrier dynamics? (e) Are electronic correlations necessary to explain extended van Hove singularities in highly doped graphene? (f) What happens to the transient band structure of heterostructures consisting of graphene and 2D Mott insulators when we excite carriers across the Mott gap? (g) Can we identify universal features in the non-equilibrium carrier dynamics that occur whenever graphene is coupled to 2D semi-conductors, topological insulators or Mott insulators? (h) Can we engineer transient band structures by phonon pumping? The different samples systems required for these endeavors will be provided by other projects.
DFG Programme
Research Units
