Hu Shiqian, Zhang Zhongwei, Jiang Pengfei, Chen Jie, Volz Sebastian, Nomura Masahiro, Li Baowen
Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, and Institute for Advanced Study , Tongji University , Shanghai 200092 , People's Republic of China.
China-EU Joint Lab for Nanophononics, School of Physics Science and Engineering , Tongji University , Shanghai 200092 , People's Republic of China.
J Phys Chem Lett. 2018 Jul 19;9(14):3959-3968. doi: 10.1021/acs.jpclett.8b01653. Epub 2018 Jul 5.
Through nonequilibrium molecular dynamics simulations, we report the direct numerical evidence of the coherent phonons participating in thermal transport at room temperature in graphene phononic crystal (GPnC) structure and evaluate their contribution to thermal conductivity based on the two-phonon model. With decreasing period length in GPnC, the transition from the incoherent to coherent phonon transport is clearly observed. When a random perturbation to the positions of holes is introduced in a graphene sheet, the phonon wave-packet simulation reveals the presence of notable localization of coherent phonons, leading to the significant reduction of thermal conductivity and suppressed length dependence. Finally, the effects of period length and temperature on the coherent phonon contribution to thermal conductivity are also discussed. Our work establishes a deep understanding of the coherent phonons transport behavior in periodic phononic structures, which provides effective guidance for engineering thermal transport based on a new path via phonon localization.
通过非平衡分子动力学模拟，我们报告了在石墨烯声子晶体（GPnC）结构中，相干声子在室温下参与热传输的直接数值证据，并基于双声子模型评估了它们对热导率的贡献。随着GPnC周期长度的减小，可以清楚地观察到从不相干声子传输到相干声子传输的转变。当在石墨烯片中引入对空穴位置的随机扰动时，声子波包模拟揭示了相干声子存在显著的局域化，导致热导率显著降低且长度依赖性受到抑制。最后，还讨论了周期长度和温度对相干声子对热导率贡献的影响。我们的工作建立了对周期性声子结构中相干声子传输行为的深入理解，这为基于声子局域化的新途径进行热传输工程提供了有效的指导。
