Lifshitz transition in titanium carbide driven by a graphene overlayer

Two-dimensional (2D) Dirac materials are electronically and structurally very sensitive to proximity effects. We demonstrate, however, the opposite effect: that the deposition of a monolayer 2D material could exercise a substantial influence on the substrate electronic structure. Here we investigate TiC(111) and show that a graphene overlayer produces a proximity effect, changing the Fermi surface topology of the TiC from six electron pockets to one hole pocket on the depth of several atomic layers inside the substrate. In addition, the graphene electronic structure undergoes an extreme modification as well. While the Dirac cone remains gapless, it experiences an energy shift of 1.0 eV beyond what was recently achieved for the Lifshitz transition of overdoped graphene. Due to this shift, the antibonding pi* band at the (M) over bar point becomes occupied and observable by photoemission.

Automated summary

We demonstrate that the deposition of a monolayer 2D material can significantly influence the electronic structure of the substrate. In our study, a graphene overlayer on TiC(111) changes the Fermi surface topology and modifies the electronic structure of graphene as well. The antibonding pi* band becomes occupied and observable by photoemission.