Band Structure Mapping of Bilayer Graphene via Quasiparticle Scattering

TL;DR

This study uses scanning tunneling microscopy to map the band structure of bilayer graphene under an electric field, revealing how the band gap and effective mass change, and extracting key tight-binding parameters.

Contribution

It provides a direct local measurement of bilayer graphene's band structure evolution under electric field using quasiparticle interference patterns.

Findings

Determined tight-binding parameters: γ₀=3.1 eV, γ₁=0.39 eV, γ₄=0.22 eV.

Observed band gap opening and effective mass modification.

Mapped quasiparticle scattering related to band structure changes.

Abstract

A perpendicular electric field breaks the layer symmetry of Bernal-stacked bilayer graphene, resulting in the opening of a band gap and a modification of the effective mass of the charge carriers. Using scanning tunneling microscopy and spectroscopy, we examine standing waves in the local density of states of bilayer graphene formed by scattering from a bilayer/trilayer boundary. The quasiparticle interference properties are controlled by the bilayer graphene band structure, allowing a direct local probe of the evolution of the band structure of bilayer graphene as a function of electric field. We extract the Slonczewski-Weiss-McClure model tight binding parameters as $\gamma_0 = 3.1$ eV, $\gamma_1 = 0.39$ eV, and $\gamma_4 = 0.22$ eV.