Gate-tunable circular phonon dichroism effect in bilayer graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Acoustics

Background:

• Circular phonon dichroism (CPD) is a phenomenon observed in 2D materials.
• Current limitations in CPD tunability hinder its practical applications.
• Exploring novel methods to control CPD is crucial for advancing 2D material functionalities.

Purpose of the Study:

• Investigate the impact of dual-gating-induced inversion symmetry breaking on CPD in bilayer graphene.
• Understand how symmetry breaking modifies phonon responses.
• Identify new pathways for tuning CPD in 2D materials.

Main Methods:

• Theoretical investigation of bilayer graphene under dual-gate electric fields.
• Analysis of phonon modes and their response to broken inversion symmetry.
• Modeling of circular phonon dichroism in different channel representations.

Main Results:

• Dual-gating induces inversion symmetry breaking, significantly altering CPD.
• Symmetry breaking modifies responses in layer-symmetric and layer-antisymmetric channels.
• Phonon dichroism emerges in the cross-channel due to symmetry breaking.
• Intralayer CPD equality is broken, and interlayer response is enhanced.

Conclusions:

• Layer degree of freedom offers a powerful tool for tuning phonon dynamics in 2D materials.
• This work provides a pathway for novel physics and applications in 2D acoustoelectronics and layertronics.
• The findings enable the development of tunable phononic devices based on symmetry control.