Project A12: Structure and Excitations of Heteroepitaxial Stacks of Weakly Interacting 2D Materials and Molecular Layers

Principle Investigator: Prof. Dr. Stefan Tautz, Dr. Francois Bocquet, Prof. Dr. Christian Kumpf (Jülich, Peter Grünberg Institut)

Summary

The twisted internal interface between two-dimensional (2D) materials is the origin of remarkable properties, most prominently the gate-controlled superconductivity in twisted bilayer graphene (TBLG).

The project explores twisted internal interfaces of graphene-related 2D materials. Epitaxy, exfoliation and stacking, as well as synthesis by interface chemistry are employed for fabrication. In the latter approach, the resulting nanographenes are manipulated with an STM/AFM tip in order to rotate and align them as desired on a substrate of choice. The influence of the twisted internal interfaces on charge-transfer and lateral charge transport is investigated in collaboration with partner projects.

We will also apply our methodology to observe ultrafast electron dynamics in time and space to the investigation of charge-transfer excitons across organic/organic, organic/2D interfaces and eventually twisted 2D interfaces.

Project-Related Publications

1. F.C. Bocquet, Y.-R. Lin, M. Franke, N. Samiseresht, S. Parhizkar, S. Soubatch, T.-L. Lee, C. Kumpf, F.S. Tautz
   Surfactant-Mediated Epitaxial Growth of Single-Layer Graphene in an Unconventional Orientation on SiC
   Phys. Rev. Lett. 125, 106102 (2020).
2. R. Wallauer, M. Raths, K. Stallberg, L. Münster, D. Brandstetter, X. Yang, J. Güdde, P. Puschnig, S. Soubatch, C. Kumpf, F.C. Bocquet, F.S. Tautz, U. Höfer
   Tracing orbital images on ultrafast time scales
   arXiv:2010.02599 (2020).
3. A. Haags, A. Reichmann, Q. Fan, L. Egger, H. Kirschner, T. Naumann, S. Werner, T. Vollgraff, J. Sundermeyer, L. Eschmann, X. Yang, D. Brandstetter, F.C. Bocquet, G. Koller, A. Gottwald, M. Richter, M.G. Ramsey, M. Rohlfing, P. Puschnig, J.M. Gottfried, S. Soubatch, F.S. Tautz
   Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization
   ACS Nano 14, 15766 (2020).
4. C. Wagner, M.F.B. Green, M. Maiworm, P. Leinen, T. Esat, N. Ferri, N. Friedrich, R. Findeisen, A. Tkatchenko, R. Temirov, F.S. Tautz
   Quantitative imaging of electric surface potentials with single-atom sensitivity
   Nat. Mater. 18, 853 (2019).
5. B.P. Klein, N.J. van der Heijden, S.R. Kachel, M. Franke, C.K. Krug, K.K. Greulich, L. Ruppenthal, P. Müller, P. Rosenow, S. Parhizkar, F.C. Bocquet, M. Schmid, W. Hieringer, R.J. Maurer, R. Tonner, C. Kumpf, I. Swart, J.M. Gottfried
   Molecular topology and surface chemical bond: Alternant versus nonalternant aromatic systems as functional structural elements
   Phys. Rev. X 9, 011030 (2019).