Controlling the layer localization of gapless states in bilayer graphene with a gate voltage

TL;DR

This paper investigates how gate voltages influence the layer localization of topological gapless states in bilayer graphene with stacking domain walls, revealing controllable switching mechanisms for potential electronic applications.

Contribution

It introduces an atomistic model and analytical Hamiltonian to explain how gate voltage controls layer localization of gapless states in bilayer graphene.

Findings

Gate voltage switches layer localization of gapless states.

States originate from single-layer graphene bands.

Model Hamiltonian explains localization as a function of potential and interlayer hopping.

Abstract

Experiments in gated bilayer graphene with stacking domain walls present topological gapless states protected by no-valley mixing. Here we research these states under gate voltages using atomistic models, which allow us to elucidate their origin. We find that the gate potential controls the layer localization of the two states, which switches non-trivially between layers depending on the applied gate voltage magnitude. We also show how these bilayer gapless states arise from bands of single-layer graphene by analyzing the formation of carbon bonds between layers. Based on this analysis we provide a model Hamiltonian with analytical solutions, which explains the layer localization as a function of the ratio between the applied potential and interlayer hopping. Our results open a route for the manipulation of gapless states in electronic devices, analogous to the proposed writing and reading memories in topological insulators.