Plasmon modes of bilayer molybdenum disulfide: a density functional study

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Bilayer molybdenum disulfide (MoS2) is a promising 2D material with unique electronic properties.
• Understanding collective electronic excitations is crucial for its application in electronic devices.
• Previous studies have not fully characterized the plasmon modes in doped bilayer MoS2.

Purpose of the Study:

• To investigate the collective electronic excitations in bilayer MoS2.
• To calculate the many-body dielectric function and electron energy-loss spectra.
• To analyze the impact of electron or hole doping on these electronic properties.

Main Methods:

• Employed density functional theory (DFT) combined with the random phase approximation (RPA).
• Utilized an ab initio based model incorporating material-realistic physical properties.
• Calculated the many-body dielectric function and electron energy-loss spectra.

Main Results:

• The electron energy-loss function is sensitive to electron or hole doping due to asymmetric band dispersions.
• Three distinct plasmon modes were predicted: a damped high-energy mode, an optical in-phase mode, and a damped acoustic out-of-phase mode.
• The optical plasmon mode exhibits specific long-wavelength dispersion characteristics originating from low-energy electron scattering.

Conclusions:

• Doping significantly influences the collective electronic excitations and plasmon modes in bilayer MoS2.
• The predicted plasmon modes offer insights into the charge dynamics of this 2D material.
• This study provides a theoretical foundation for experimental investigations of electronic excitations in MoS2-based heterostructures.