Topological plasmons in stacked graphene nanoribbons

Area of Science:

• Condensed Matter Physics
• Materials Science
• Photonics

Background:

• Topological insulators exhibit unique edge and surface states protected by time-reversal symmetry.
• Graphene nanoribbons (GNRs) offer tunable electronic and optical properties.
• The Su-Schrieffer-Heeger (SSH) model describes topological phases in one-dimensional systems.

Purpose of the Study:

• To theoretically investigate topological plasmons in stacked graphene nanoribbon (GNR) layers.
• To explore the emergence of topological modes in two-dimensional (2D) GNR arrays.
• To provide a platform for designing topological photonic devices.

Main Methods:

• Theoretical study of topological plasmons.
• Application of the Su-Schrieffer-Heeger (SSH) model to GNRs.
• Analysis using the Zak phase for 1D and 2D systems.

Main Results:

• In 1D stacked GNRs, two topological modes localized in the top/bottom layers are predicted by the Zak phase.
• In 2D GNR arrays, the 2D Zak phase predicts three types of topological modes: edge, surface, and corner.
• A 2D ribbon array (Nx × Ny) hosts 4(Ny - 1) edge, 4(Nx - 1) surface, and 4 corner modes with localized fields.

Conclusions:

• This work establishes GNRs as a viable platform for realizing topological modes.
• The findings are significant for the development of topological photonic devices like lasers and sensors.
• The study demonstrates the control and prediction of topological phenomena in engineered GNR structures.