Midinfrared Plasmonic Valleytronics in Metagate-Tuned Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanophotonics

Background:

• Graphene exhibits unique electronic properties exploitable for advanced nanophotonic devices.
• Surface plasmons in graphene offer potential for nanoscale light manipulation.
• Controlling plasmon propagation and topological properties is crucial for device applications.

Purpose of the Study:

• To propose and demonstrate a valley plasmonic crystal for graphene surface plasmons.
• To investigate the use of a designer metagate for controlling graphene's Fermi energy landscape.
• To explore the topological properties and guiding capabilities of engineered plasmonic structures.

Main Methods:

• Designing and fabricating a metagate structure positioned near graphene.
• Imposing a periodic Fermi energy landscape on graphene using the metagate.
• Analyzing the resulting band structure for plasmon propagation and topological features.
• Simulating the guiding of localized plasmons along domain walls.

Main Results:

• Demonstrated complete propagation band gaps for graphene surface plasmons.
• Achieved nontrivial valley-linked topological properties in the plasmonic crystal.
• Showcased reflectionless guiding of highly localized plasmons along curved domain walls.
• Confirmed suppression of intervalley scattering.

Conclusions:

• The proposed metagate-graphene structure functions as a valley plasmonic crystal.
• This approach enables nonmagnetic and dynamically reconfigurable topological nanophotonic devices.
• The findings open new avenues for advanced plasmonic technologies.