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arXiv 0902.3350cond-mat.dis-nncond-mat.stat-mech
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质量无序谐振晶体中的热输运和声子局域化

Heat transport and phonon localization in mass-disordered harmonic crystals

Abhishek Chaudhuri, Anupam Kundu, Dibyendu Roy, Abhishek Dhar, Joel L. Lebowitz, Herbert Spohn

摘要:

本文研究了二维和三维无序简谐晶体中的稳态热流,该晶体在边界处连接到不同温度的随机白噪声热浴中,无序导致短波长声子模局域化,因此该系统中的热流由扩展声子模携带,这些扩展声子模可以是扩散的也可以是弹道的。使用本地化理论和动力学理论的想法,我们估计各种模式的热流的贡献,并从这个我们得到的渐近系统的大小依赖的电流。这些估计进行了比较,从一个精确的公式的电流,给出的频率传输函数,以及从直接的非平衡模拟的数值评估得到的结果。这些产生了强烈的依赖于边界条件的热通量。我们的分析参数表明,对于现实的边界条件的电导率是有限的,在三维空间,但我们无法验证这一数字,除了在系统受到外部钉扎电位的情况下。这种情况下是密切相关的问题的本地化的电子在一个随机的潜力,在这里,我们数值验证,钉扎三维系统满足傅立叶定律,而二维系统是一个热绝缘体。我们还研究了不同的正常模式的反参与比。

英文摘要:

We investigate the steady state heat current in two and three dimensional disordered harmonic crystals in a slab geometry, connected at the boundaries to stochastic white noise heat baths at different temperatures.The disorder causes short wavelength phonon modes to be localized so the heat current in this system is carried by the extended phonon modes which can be either diffusive or ballistic. Using ideas both from localization theory and from kinetic theory we estimate the contribution of various modes to the heat current and from this we obtain the asymptotic system size dependence of the current. These estimates are compared with results obtained from a numerical evaluation of an exact formula for the current, given in terms of a frequency transmission function, as well as from direct nonequilibrium simulations. These yield a strong dependence of the heat flux on boundary conditions. Our analytical arguments show that for realistic boundary conditions the conductivity is finite in three dimensions but we are not able to verify this numerically, except in the case where the system is subjected to an external pinning potential. This case is closely related to the problem of localization of electrons in a random potential and here we numerically verify that the pinned three dimensional system satisfies Fourier's law while the two dimensional system is a heat insulator. We also investigate the inverse participation ratio of different normal modes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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