Directly visualizing the crossover from incoherent to coherent phonons in two-dimensional periodic MoS2/MoSe2 arrayed heterostructure
Directly visualizing the crossover from incoherent to coherent phonons in two-dimensional periodic MoS2/MoSe2 arrayed heterostructure
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DOI：
10.1016/j.ijheatmasstransfer.2021.121630
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发表时间：
2021-07-02
影响因子：
5.2
通讯作者：
Zhang, Xing
中科院分区：
文献类型：
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作者：
An, Meng;Chen, Dongsheng;Zhang, Xing
最近，人们在利用各种周期性纳米结构中的相干声子来控制热输运方面做了大量的工作。然而，组成材料之间的本征晶格差异不可避免地在界面处产生无序，从而限制了直接观察相干声子输运的机会。在这里，我们用非平衡分子动力学模拟研究了具有最小晶格失配的周期MoS_2/MoSe_2阵列异质结中相干声子输运的可控性和可视化。研究发现，通过调节MoSe_2纳米点阵列的密度，可以破坏和重建相干声子输运。基于空间能量分布和简谐分析，可视化了由关联破坏引起的声子局域化。此外，本征矢量图提供了局域声子模式的清晰可视化。此外，通过减小周期长度可以重建声子的关联，从声子色散曲线中提取的增强的群速度证实了这一点。有趣的是，从非相干声子输运到相干声子输运的交叉是由空间能量分布和光谱声子传输系数直接观察到的。最后，还讨论了导热系数的大小和温度关系。研究声子相干性及其对导热系数的可视化调控，将有助于在实际应用中进行精细的热控制和管理。(C)2021年爱思唯尔有限公司。保留所有权利。
Recently, massive efforts have been done on controlling thermal transport via coherent phonons in the various periodic nanostructures. However, the intrinsic lattice difference between the constituent materials inevitably generates the disorder at the interfaces, thus limiting the opportunity of directly observing the coherent phonon transport. Here, we investigate the controllability and visualization of the coherent phonon transport in a periodic MoS2/MoSe2 arrayed heterostructure with minimum lattice mismatching using non-equilibrium molecular dynamics simulation. It is found that the coherent phonon transport can be destroyed and rebuilt through adjusting the density of MoSe2 nanodot arrays. The phonon localization induced by the destruction of correlation is visualized based on the spatial energy distribution and an harmonic analysis. Furthermore, the eigen vector diagrams provide a distinct visualization of the localized phonon modes. Besides, the correlation of phonon can be rebuilt by reducing the period length, which is verified by the enhanced group velocities extracted from phonon dispersion curves. Interestingly, the crossover from incoherent to coherent phonon transport is directly observed by the spatial energy distributions and the spectral phonon transmission coefficients. Finally, the size and temperature dependence of thermal conductivity are also discussed. This study of the phonon coherence and its visualizing manipulation on thermal conductivity will be beneficial to fine heat control and management in the real applications. (C) 2021 Elsevier Ltd. All rights reserved.