Van Hove singularity and Lifshitz transition in thickness-controlled Li-intercalated graphene

We demonstrate a method to control the Fermi level around the Van Hove singularity (VHS) in Li-intercalated graphene on the SiC substrate. By angle-resolved photoemission spectroscopy, we observed a clear Lifshitz transition in the vicinity of the VHS when the thickness of graphene exceeds four layers. We calculated the band structure of a multilayer system with different stacking sequences of graphene and Li layer. The so-called stage 2 model reproduces the Lifshitz transition, where Li occupies every other interlayer of graphene. In addition, we found that a sizable Schottky barrier is formed between graphene and the substrate. These properties allow us to explore the electronic phase diagram around the VHS by controlling the thickness.

Automated summary

We demonstrate a method to control the Fermi level around the Van Hove singularity (VHS) in Li-intercalated graphene on the SiC substrate. By observing a clear Lifshitz transition in the vicinity of the VHS when the thickness of graphene exceeds four layers, we calculate the band structure of a multilayer system with different stacking sequences of graphene and Li layer. Furthermore, a sizable Schottky barrier is formed between graphene and the substrate, allowing us to explore the electronic phase diagram around the VHS by controlling the thickness.