Asymmetry-enriched electronic and optical properties of bilayer graphene

Bor-Luen Huang,Ming-Fa Lin,Chih-Piao Chuu

doi:10.1038/s41598-018-37058-9

Bor-Luen Huang, Ming-Fa Lin + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-37058-9

Copy DOI

Abstract

The electronic and optical response of Bernal stacked bilayer graphene with geometry modulation and gate voltage are studied. The broken symmetry in sublattices, one dimensional periodicity perpendicular to the domain wall and out-of-plane axis introduces substantial changes of wavefunctions, such as gapless topological protected states, standing waves with bonding and anti-bonding characteristics, rich structures in density of states and optical spectra. The wavefunctions present well-behaved standing waves in pure system and complicated node structures in geometry-modulated system. The optical absorption spectra show forbidden optical excitation channels, prominent asymmetric absorption peaks, and dramatic variations in absorption structures. These results provide that the geometry-modulated structure with tunable gate voltage could be used for electronic and optical manipulation in future graphene-based devices.

Highlights

The layered structure materials have stimulated enormous studies in the condensed matter and high-energy physics community
The domain wall (DW) formed in between by two oppositely biased region of Bilayer graphenes (BLGs) is first proposed by Martin et al.[16] to host one-dimensional topological states, which is distinct from the edge states in nature[17]
Tight-binding functions on distinct sublattices, and Density of states (DOS) by exact diagonalization

Summary

Introduction

The layered structure materials have stimulated enormous studies in the condensed matter and high-energy physics community. Bilayer graphenes (BLGs) with AB or AA stacking possess different electronic structures[9], absorption spectra[10], and Coulomb excitations[11] from each other. An alternative approach is to exploit different stacking orders, which creates diverse new physics in multi-layer system[18] Such crystalline topological line defects exist naturally in Bernal stacked BLGs grown by chemical vapour deposition (CVD)[20,21,22] and in exfoliated BLGs from graphite[23,24,25]. The band structures show diverse 1D phenomena, including 1D energy subbands with various band-edge states, band splitting through geometry modulation, and metallic behavior in geometry-modulated system with a gate voltage. Our predicted results could be verified by the experimental measurements

Methods

Results

Conclusion