Plasmon Reflections by Topological Electronic Boundaries in Bilayer Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Domain walls in bilayer graphene are topological electronic boundaries and nanoscale plasmonic scatterers.
• These domain walls separate regions of AB and BA interlayer stacking.

Purpose of the Study:

• To investigate the strong coupling between domain walls and surface plasmons.
• To elucidate the role of topological chiral modes in this interaction.
• To understand the observed plasmon reflection and interference patterns.

Main Methods:

• Infrared nanoimaging experiments to observe plasmonic behavior.
• Computational methods to determine the electronic structure of domain walls.
• Analysis of optical transitions and local conductivity.

Main Results:

• Strong coupling of domain walls to surface plasmons is attributed to topological chiral modes.
• Optical transitions enhance local conductivity, causing plasmon reflection.
• Two types of plasmonic standing-wave patterns observed, linked to shear and tensile domain walls.
• Tensile domain walls exhibit additional confined bands, creating structure-specific conductivity contrast.

Conclusions:

• The coupling mechanism between confined modes and surface plasmon scattering is a key factor in plasmon control.
• This phenomenon is likely applicable to other topological electronic boundaries in van der Waals materials.
• The findings offer a new pathway for manipulating plasmons in nanostructures.