Plasmons and screening in monolayer and multilayer black phosphorus

Area of Science:

• Condensed matter physics
• Materials science
• Solid-state physics

Background:

• Black phosphorus possesses anisotropic electronic band structures.
• Understanding electronic properties is crucial for novel material applications.

Purpose of the Study:

• Investigate the electronic screening and collective excitations in black phosphorus.
• Analyze the impact of band anisotropy on these properties.

Main Methods:

• Theoretical analysis of electronic band structure.
• Application of a nonlinear Thomas-Fermi model.
• Examination of screening and charge distribution.

Main Results:

• In-plane static screening is largely isotropic for relevant momenta.
• Collective electronic excitations (plasmons) show strong anisotropy.
• Plasmon frequency scales with carrier concentration as nβ, with β<1/2 due to band nonparabolicity.

Conclusions:

• Black phosphorus exhibits distinct behaviors in static screening and dynamic excitations.
• Band nonparabolicity significantly influences plasmon properties.
• Theoretical models provide insights into charge dynamics in anisotropic materials.