Akhiezer mechanism limits coherent heat conduction in phononic crystals
Akhiezer mechanism limits coherent heat conduction in phononic crystals
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阿希泽机制限制声子晶体中的相干热传导
DOI：
10.1103/physrevb.98.134307
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发表时间：
2018
影响因子：
3.7
通讯作者：
Shiomi Junichiro
中科院分区：
文献类型：
--
作者：
Liao Yuxuan;Shiga Takuma;Kashiwagi Makoto;Shiomi Junichiro
声子晶体（PnCs）中的热量由声子携带，声子可以根据模式，温度和长度尺度表现为相干（类波）或非相干（类粒子）。通过比较PnCs的实测热导率与理论，最近的工作表明，PnCs的热导率可以解释只考虑表面和边界散射，这不仅后向散射声子，但也打破了他们的相干性。这里的逻辑是，由于平均声子波长在室温下只有几个纳米，表面和边界的粗糙度使散射扩散（破坏声子的相位相干性），因此只有非常长的波长（低频）声子对总热导率的贡献可以忽略不计。在这里，我们从理论上表明，在一个薄膜PnCs，低频相干声子可以显着地有助于热导率时，假设三声子散射模型的内禀散射，因为它们的极高的态密度，导致从低维的性质。然而，进一步的分析表明，由于Akhiezer机制，在130至300 K的温度范围内，低频相干声子的贡献仍然可以忽略不计，这恰当地回答了为什么PnCs的热导率可以通过仅考虑非相干声子在这些温度下的散射来解释的问题。
Heat in phononic crystals (PnCs) is carried by phonons, which can behave coherently (wave-like) or incoherently (particle-like) depending on the modes, temperature, and length scales. By comparing the measured thermal conductivity of PnCs with theories, recent works suggest that thermal conductivity of PnCs can be explained by considering only surface and boundary scatterings, which not only backscatter phonons but also break their coherence. The logic here is that since average phonon wavelength at room temperature is only a few nanometers, the roughness at the surfaces and boundaries make the scattering diffusive (break the phase coherence of phonons), and thus only very long wavelength (low frequency) phonons with negligible contribution to total thermal conductivity remain coherent. Here, we theoretically show that in a thin film PnCs, the low frequency coherent phonons could significantly contribute to thermal conductivity when assuming the three-phonon scattering model for intrinsic scattering because of their extremely large density of states that result from the low dimensional nature. Yet, further analysis shows the contribution of the low frequency coherent phonons is still negligible within temperature range from 130 to 300 K due to the Akhiezer mechanism, which properly answers the question why the thermal conductivity of PnCs can be explained by considering only scattering of incoherent phonons at these temperatures.
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影响因子：
3.7
作者：
Atalaya, Juan;Kenny, Thomas W.;Dykman, M. I.
通讯作者：
Dykman, M. I.
脏电介质晶体中的超声波衰减
影响因子：
--
作者：
H. Maris
通讯作者：
H. Maris
影响因子：
3.7
作者：
R. Anufriev;M. Nomura
通讯作者：
R. Anufriev;M. Nomura
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
M. Nomura;R. Yanagisawa;J. Maire;R. Anufriev;and S. Volz
通讯作者：
and S. Volz
影响因子：
13.6
作者：
Maire J;Anufriev R;Yanagisawa R;Ramiere A;Volz S;Nomura M
通讯作者：
Nomura M