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

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Electrostatic gating is crucial in materials science but its direct impact on electronic band structure remains elusive.
• Angle-resolved photoemission spectroscopy (ARPES) is the primary technique for probing electronic band structures.

Purpose of the Study:

• To directly visualize the effects of electrostatic gating on the electronic band structure of bilayer graphene using ARPES.
• To investigate the electric field effect in a graphene-hexagonal boron nitride heterostructure.

Main Methods:

• Utilized a state-of-the-art ARPES setup with submicron spatial resolution.
• Investigated a heterostructure of Bernal-stacked bilayer graphene (BLG) on hexagonal boron nitride (hBN) on a graphite flake.
• Applied voltage biasing to the graphite flake to induce an electric field effect.

Main Results:

• Directly visualized the electric field effect on the valence band and carbon 1s core level of BLG.
• Observed band gap opening in BLG under a transverse electric field.
• Highlighted the significance of intra-layer screening in the observed phenomena.

Conclusions:

• This study provides the first direct ARPES visualization of electrostatic gating effects on bilayer graphene's electronic band structure.
• The findings offer new avenues for studying electric field effects in materials using momentum-resolved electronic structure.
• Emphasizes the role of intra-layer screening in understanding gated materials.