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arXiv 1407.6679cond-mat.mes-hall
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碳纳米管在低温和超低温区的振动heat capacity

Vibrational heat capacity of carbon nanotubes in low and ultra-low temperature regions

M. V. Avramenko, I. Yu. Golushko, A. E. Myasnikova, S. B. Rochal

摘要:

我们建立了单壁碳纳米管(SWCNTs)与环境弱相互作用的低频动力学连续理论。在所提出的方法的框架下,我们得到了在低温(T<40 K)和超低温(T<2.5 K)范围内的单壁碳纳米管比热随温度的变化关系。我们考虑到在单壁碳纳米管和环境之间的耦合,稍微增加了那些单壁碳纳米管模式,其中主要具有径向偏振的频率的主要条款。这种耦合大大降低了最低频率区域的声子态密度。理论上预测的比热在T<2.5 K的区间内的下降,与前面的方法相比,正确地解释了现有的实验数据。提出的理论可以为许多其他单壁和多壁管状结构(氮化硼,过渡金属二硫属化物),在过去的十年中出现的低温热容量和声子动力学的研究的基础。

英文摘要:

We develop a continuous theory of low-frequency dynamics for single-walled carbon nanotubes (SWCNTs) weakly interacting with the environment. In the frame of the approach proposed we obtain temperature dependence of SWCNTs specific heat in the low (T<40 K) and ultra-low (T<2.5 K) temperature ranges. We take into account the main term in the coupling between SWCNT and the environment that slightly increases the frequencies of those SWCNT modes, which possess predominantly radial polarization. The coupling drastically decreases the density of phonon states in the lowest frequencies region. The theoretically predicted fall of the specific heat in the interval T<2.5 K properly explains available experimental data in contrast to the preceding approaches. The theory proposed can be the basis for studies of low-temperature heat capacity and phonon dynamics of many other single-walled and multi-walled tubular structures (boron nitride, transition metal dichalcogenides) which have emerged in the past decade.

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