Thermal conductivity study of 2D Si₄C₈ materials by anharmonic phonon renormalization

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Accurate thermal conductivity prediction is vital for 2D materials.
• Conventional methods using harmonic phonons fail for materials like 2D silicon-carbon (Si-C) due to imaginary frequencies.
• Quartic (fourth-order) phonon scattering significantly impacts heat transport.

Purpose of the Study:

• To analyze thermal conductivity in 2D carbon materials, specifically Si₄C₈.
• To investigate the influence of quartic scattering on heat transport.
• To establish a systematic computational methodology for 2D Si-C thermal properties.

Main Methods:

• Employed anharmonic phonon renormalization.
• Integrated self-consistent phonon (SCP) theory with the Boltzmann transport equation (BTE).
• Addressed quartic anharmonic effects, including four-phonon (4ph) scatterings and temperature-dependent phonon frequency shifts.

Main Results:

• Demonstrated the inadequacy of harmonic BTE calculations for 2D Si-C.
• Showcased the critical role of anharmonicity renormalization for precise thermal conductivity evaluation.
• Established a coherent temperature dependency for the thermal conductivity of 2D Si₄C₈.

Conclusions:

• Anharmonic phonon renormalization is essential for accurate thermal conductivity calculations in 2D Si-C materials.
• The integrated SCP-BTE approach effectively captures complex phonon scattering mechanisms.
• Provides a framework for understanding structure-property relationships in 2D Si-C phases.