Electron Correlation and Electron-Phonon coupling in a Trilayer Graphene/hBN Moire Superlattice

When two-dimensional materials with similar lattice constants are stacked vertically, spatial modulation can be induced in the form of moire superlattices. Such superlattices emerged as a novel platform to engineer interlayer interactions between electrons and phonons, which have resulted in correlated and topological electron phenomena. The experimental study of 2D moire superlattices, however, is quite challenging for conventional spectroscopy techniques. In this talk, I will show optical spectroscopy study of a particular moire superlattice that is formed between ABC trilayer graphene and hexagonal boron nitride. I will first show our FTIR photocurrent spectroscopy study of the bandstructure of moire mini-bands, and its implications on the formation of correlated electron ground states. Furthermore, I will show our observation of a strong interlayer electron-phonon coupling that is unique to moire superlattices. These results point to exciting opportunities in engineering and understanding of electronic and optical properties of 2D moire superlattices.

Host: Xiao-Xiao Zhang