Van Hove Singularity and Lifshitz Transition in Thickness-Controlled Li-Intercalated Graphene

TL;DR

This paper presents a method to control the Fermi level near the van Hove singularity in Li-intercalated graphene, revealing a Lifshitz transition influenced by substrate effects, enabling exploration of electronic phases.

Contribution

It introduces a new approach to tune the Fermi level around the van Hove singularity in Li-intercalated graphene using thickness control and substrate interactions.

Findings

Observation of Lifshitz transition near VHS with increasing graphene thickness

Substrate stabilizes Fermi level via hybridization effects

Formation of a sizable Schottky barrier at the graphene-substrate interface

Abstract

We demonstrate a new 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 by increasing the graphene thickness. This behavior is unexpected in a free-standing Li-intercalated graphene model. The calculation including the substrate suggests that the surface state stabilizes the Fermi level around the VHS of the Dirac bands via hybridization. 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 and electric field in the device condition.