Phonon Transport in Defect-Laden Bilayer Janus PtSTe Studied Using Neural-Network Force Fields.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Understanding thermal transport in 2D materials is crucial for thermoelectric applications.
• Defects are known to influence material properties, but their specific impact on phonon transport in bilayer PtSTe requires detailed investigation.

Purpose of the Study:

• To investigate the effect of defects on the phonon transport properties of bilayer PtSTe.
• To quantify the reduction in thermal conductivity caused by different types of defects.
• To explore the underlying mechanisms responsible for altered phonon behavior.

Main Methods:

• Equilibrium molecular dynamics (EMD) simulations were employed.
• A neural-network force field was utilized for accurate atomic interactions.
• Projected phonon density of states (PDOS) analysis was performed.

Main Results:

• Defects were found to be highly effective in reducing thermal conductivity.
• Flower defects demonstrated a significant impact on thermal conductivity, comparable to double vacancies.
• An unusual temperature dependence of thermal conductivity was observed for structures with flower defects, linked to high-temperature structural instability.
• Localized phonon modes and blue shifts were identified around defect sites.

Conclusions:

• Defects, particularly flower defects, are potent phonon scatterers in bilayer PtSTe, drastically lowering thermal conductivity.
• Structural instability at elevated temperatures introduces unique temperature-dependent thermal transport characteristics.
• The study provides insights into defect-induced phonon scattering mechanisms and their influence on material properties.