Verification of the phonon relaxation time approximation by probing the relaxation process of a single excited mode
Verification of the phonon relaxation time approximation by probing the relaxation process of a single excited mode
复制标题
通过探测单激发模式的弛豫过程验证声子弛豫时间近似
DOI：
10.1103/physrevb.100.214116
复制
发表时间：
2019
影响因子：
3.7
通讯作者：
Takuma Hori
中科院分区：
文献类型：
--
作者：
瀬戸浦 健仁;辻 徹郎;伊都 将司;川野 聡恭;宮坂 博;Takuma Hori
模拟了氩气晶体中单声子模式的弛豫过程，探讨了当声子模式受到较大的激发时，微扰理论是否仍然成立。根据模态对平衡态的贡献，将位移和速度相加，得到激发态。弛豫曲线呈指数衰减，符合声子散射的微扰理论。从弛豫曲线得到的散射率随着激发模温度的升高而增加。然而，散射速率的差异小于激发模温度的差异；当激发态的温度比平衡态的温度高50倍时，典型的增加率仍为20%。这种趋势也存在于硅晶体中，硅晶体是一种更为现实和复杂的材料。结果表明，即使在较大的非平衡条件下，松弛时间近似也是有效的。结果还表明，当一个声子模式被激发到高温时，其他声子模式的散射率增加。还研究了极低平衡态温度下的弛豫。能量的时间变化表现出在高温下所缺乏的指数型衰减和振荡。分析了平衡态温度和激发态温度对振荡幅度和频率的影响。结果表明，振荡的幅度取决于两者的温度，而频率仅受激励模式温度的影响。
The relaxation process of the single-phonon modes excited in an argon crystal is simulated to investigate whether the perturbation theory still works when a phonon mode is subject to a large excitation. The excited modes are attained by adding the displacements and velocities according to the contribution of the modes to those of equilibrium states. The relaxation curves exhibit exponential decay, which agrees with the perturbation theory of phonon scattering. The scattering rates obtained from the relaxation curves increase with the temperature of the excited modes. However, the difference between the scattering rates is less than that of the excited mode temperature; the typical rate of increase is 20% even when the temperature of the excited mode is 50 times larger than that of the equilibrium state. This tendency is also found in a silicon crystal, which is a more realistic and complex material. From these results, it is revealed that the relaxation time approximation is also valid even under large nonequilibrium condition. The results also show that the scattering rates of the other phonon modes increase when one mode is excited to a high temperature. The relaxation at extremely low equilibrium state temperature is also investigated. The temporal variation of the energies shows exponential-like decay and oscillation that is lacking at high temperature. The influence of the temperature of the equilibrium state and the excited mode on the oscillation amplitude and frequency is evaluated. The results indicate that the amplitude of the oscillation depends on the temperature of both, whereas the frequency is only affected by the temperature of the excitation mode.
影响因子：
3.2
作者：
Larkin, Jason M.;McGaughey, Alan J. H.
通讯作者：
McGaughey, Alan J. H.
小尺度声子输运的偏差方法
DOI：
10.1299/mer.2014fe0013
发表时间：
2014
期刊：
影响因子：
--
作者：
Jean;C. Landon;N. Hadjiconstantinou
通讯作者：
N. Hadjiconstantinou
长程和短程有序对 SiGe 合金热导率的影响：分子动力学模拟
DOI：
10.1103/physrevb.91.180302
发表时间：
2015
期刊：
影响因子：
--
作者：
Christopher H. Baker;P. Norris
通讯作者：
P. Norris