Visualizing the Effect of an Electrostatic Gate with Angle-Resolved Photoemission Spectroscopy

TL;DR

This study uses advanced angle-resolved photoemission spectroscopy to directly visualize how electrostatic gating influences the electronic band structure of bilayer graphene on boron nitride, revealing band gap changes and screening effects.

Contribution

It demonstrates the first direct visualization of electrostatic gating effects on electronic band structure using high-resolution ARPES on a heterostructure.

Findings

Electric field effect visualized on valence band and core levels

Band gap opening in bilayer graphene under transverse electric field

Intralayer screening effects highlighted

Abstract

Electrostatic gating is pervasive in materials science, yet its effects on the electronic band structure of materials has never been revealed directly by angle-resolved photoemission spectroscopy (ARPES), the technique of choice to non-invasively probe the electronic band structure of a material. By means of a state-of-the-art ARPES setup with sub-micron spatial resolution, we have investigated a heterostructure composed of Bernal-stacked bilayer graphene (BLG) on hexagonal boron nitride and deposited on a graphite flake. By voltage biasing the latter, the electric field effect is directly visualized on the valence band as well as on the carbon 1s core level of BLG. The band gap opening of BLG submitted to a transverse electric field is discussed and the importance of intralayer screening is put forward. Our results pave the way for new studies that will use momentum-resolved electronic structure information to gain insight on the physics of materials submitted to the electric field effect.