Spectral energy analysis of locally resonant nanophononic metamaterials by molecular simulations
Spectral energy analysis of locally resonant nanophononic metamaterials by molecular simulations
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DOI：
10.1103/physrevb.93.081412
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发表时间：
2016-02-26
影响因子：
3.7
通讯作者：
Hussein, Mahmoud I.
中科院分区：
文献类型：
--
作者：
Honarvar, Hossein;Hussein, Mahmoud I.
纳米声子超材料是一种新型的纳米结构材料，具有阵列或森林的本质分布共振子结构。每个子结构都表现出许多局部共振，每个局部共振都可能与底层宿主材料的声子色散杂化，导致群速度显著降低，从而导致晶格热导率降低。在这个快速通信中，分子动力学模拟被用于研究纳米声子超材料结构的动力学和热输运性质，该结构由自由悬浮的硅膜和一系列硅纳米柱组成。模拟结果与先前基于晶格动力学的预测一致，即由于局部谐振器的存在，热导率降低。使用光谱能量密度方法，其中只利用模拟数据，没有提供纳米结构共振声子模式的先验信息，我们直接证明共振杂交的存在是一种内在机制，有助于减缓宿主介质中的热输运。
A nanophononic metamaterial is a new type of nanostructured material that features an array, or a forest, of intrinsically distributed resonating substructures. Each substructure exhibits numerous local resonances, each of which may hybridize with the phonon dispersion of the underlying host material, causing significant reductions in the group velocities and consequently a reduction in the lattice thermal conductivity. In this Rapid Communication, molecular dynamics simulations are utilized to investigate both the dynamics and the thermal transport properties of a nanophononic metamaterial configuration consisting of a freely suspended silicon membrane with an array of silicon nanopillars standing on the surface. The simulations yield results consistent with earlier lattice-dynamics-based predictions which showed a reduction in the thermal conductivity due to the presence of the local resonators. Using a spectral energy density approach, in which only simulation data are utilized and no a priori information on the nanostructure resonant phonon modes is provided, we show direct evidence of the existence of resonance hybridizations as an inherent mechanism contributing to the slowing down of thermal transport in the host medium.