Disorder limits the coherent phonon transport in two-dimensional phononic crystal structures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Controlling thermal transport using coherent phonons in phononic structures is an active research area.
• Experimental observation of coherent phonon transport at room temperature is challenging.
• The precise contribution of coherent phonons to overall thermal conductivity remains under-assessed.

Purpose of the Study:

• To investigate coherent phonon transport in C3N phononic crystals (CNPnC) at room temperature.
• To analyze the impact of varying porosity and structural disorder on thermal conductivity.
• To understand the fundamental mechanisms governing coherent phonon behavior in these structures.

Main Methods:

• Non-equilibrium molecular dynamics (NEMD) simulations were employed.
• Analysis included phonon transmission coefficient, wave packet simulations, participation ratio, and spatial energy density.
• Simulations were conducted on both ordered CNPnC and disordered C3N (D-C3N) structures.

Main Results:

• Disordered C3N structures with randomly distributed pores exhibited significant localization of coherent phonons.
• This phonon localization led to a substantial reduction in thermal conductivity compared to ordered structures.
• The study also examined the influence of length, temperature, and strain on thermal transport.

Conclusions:

• Coherent phonon localization in disordered phononic structures is a key mechanism for reducing thermal conductivity.
• The findings provide a foundational understanding of coherent phonon transport dynamics.
• This research is valuable for designing phononic materials for advanced thermal control applications.