Low-temperature thermal conductances of amorphous dielectric microbridges in the diffusive to ballistic transition
Low-temperature thermal conductances of amorphous dielectric microbridges in the diffusive to ballistic transition
复制标题
非晶介电微桥在扩散到弹道转变过程中的低温热导
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
A. Velichko
中科院分区：
文献类型：
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作者：
S. Withington;D. Goldie;A. Velichko
通过一个有耗声波模型，我们探讨了非弹性散射对非晶介质微桥在扩散到弹道过渡的低温热导率的影响。该模型不仅给出了作为几何形状和温度的函数的热通量，而且给出了构成损失的内部自由度的温度分布，这反过来又可用于计算噪声。该方法导致强大的概念见解，并提供了一个数值框架，用于分析实验数据。Si${}_{x}$N${}_{y}$倾向于在低频下表现为弹道，在高频下表现为扩散，并且当在所有频率上积分时，扩散到弹道的转变在大约几百微米的长度处变得明显。可能包括通量相关的声学损失，这导致违反直觉的热行为。当使用小的温差测量时，样品可以表现为扩散，但是当使用大的温差测量时，样品可以表现为弹道。有令人信服的间接证据表明，声饱和的影响已经看到，但没有明确认识到，在许多场合。
Through a lossy acoustic-wave model we explore the effect of inelastic scattering on the low-temperature thermal conductances of amorphous dielectric microbridges in the diffusive to ballistic transition. The model gives not only the thermal flux as a function of geometry and temperature, but also the temperature distribution of the internal degrees of freedom that constitute the loss, which in turn can be used for calculating noise. The approach leads to powerful conceptual insights and provides a numerical framework for analyzing experimental data. Si${}_{x}$N${}_{y}$ tends to behave ballistically at low frequencies and diffusively at high frequencies, and when integrated over all frequency, the diffusive to ballistic transition becomes apparent at lengths of around a few hundred microns. It is possible to include flux-dependent acoustic loss, which leads to counterintuitive thermal behavior. A sample can behave diffusively when measured using a small temperature difference, but ballistically when measured using a large temperature difference. There is compelling circumstantial evidence that the effects of acoustic saturation have been seen, but not explicitly recognized, on many occasions.