Plasmonic responses in Janus bAsP with elliptic-to-hyperbolic transition: an ab-initio study

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanophotonics

Background:

• Tunable plasmonic responses, especially the transition between elliptic and hyperbolic regimes, are rare in materials.
• Surface plasmon polaritons (SPPs) are crucial for nanoscale optical phenomena and applications.

Purpose of the Study:

• To theoretically investigate the plasmonic properties of Janus black arsenic phosphorus (bAsP).
• To explore the possibility of tuning elliptic-to-hyperbolic transitions in bAsP through doping and strain.
• To examine the plasmonic behavior of bAsP-graphene heterostructures.

Main Methods:

• Ab-initio calculations were employed to study the electronic band structure and dielectric function of bAsP.
• The effects of electron doping, strain (along armchair and zigzag directions), and heterostructure formation on plasmonic responses were analyzed.

Main Results:

• Janus bAsP supports both elliptic and hyperbolic in-plane SPPs in the infrared upon electron doping.
• Anisotropic plasmonic responses were observed in the elliptic regime due to anisotropic band dispersions.
• In the hyperbolic regime, unique permittivity characteristics arise from differing Drude plasma frequencies and interband contributions.
• Strain engineering, particularly along the zigzag direction, modifies band structure and plasmonic responses, enabling an indirect-bandgap state and altered plasma frequencies.
• A special hyperbolic case with reversed permittivity signs was identified under combined strain and doping.
• bAsP-graphene heterostructures exhibit strong plasmonic behavior without external doping due to charge transfer.

Conclusions:

• Janus bAsP is a promising material for actively tunable plasmonic devices.
• The ability to switch between elliptic and hyperbolic plasmonic responses via doping and strain offers significant design flexibility.
• bAsP-based heterostructures present a viable route for enhanced plasmonic applications in the infrared spectrum.