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arXiv 0801.4120cond-mat.mes-hallcond-mat.mtrl-sci
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碳纳米管的电子和光学性质对高频场的依赖性

Dependence of electronic and optical properties on a high-frequency field for carbon nanotubes

Wenhu Liao, Guanghui Zhou, Kai-He Ding

摘要:

本文从理论上研究了连接在两个正常导体引线上的锯齿形单壁碳纳米管在低温下外电磁场照射下的电子结构、输运和光学性质,特别强调了高频响应的特征。利用标准的非平衡格林函数方法,我们分别研究了光子极化方向与隧穿电流方向平行的系统的时均态密度、电导率、介电函数和电子能量损失谱。通过数值算例表明,态密度强烈地依赖于入射电子的能量、外加场的强度和频率。当电子能量高于铅-纳米管耦合能量时,体系电导分别随电场强度的增大而减小,随电场频率的增大而增大,并呈现出振荡结构。此外,随着场频的变化,系统的光学函数也具有丰富的结构。这表明这种输运对外场参数的依赖性可以用来给出碳纳米管的能谱信息和探测高频微波辐射。

英文摘要:

We study theoretically the electronic structure, transport and optical properties for a zigzag single-wall carbon nanotube connected to two normal conductor leads under the irradiation of an external electromagnetic field at low temperatures, with particular emphasis on the features of high-frequency response. Using the standard nonequilibrium Green's function techniques, we examine the time-averaged density of states, the conductivity, the dielectric function and the electron energy loss spectra for the system with photon polarization parallel with the tunneling current direction, respectively. Through some numerical examples, it is shown that the density of states is strongly dependent on the incident electron energy, the strength and frequency of the applied field. For higher electron energies in comparison with lead-nanotube coupling energy, the system conductance decreases with increasing the field strength and increases with increasing the field frequency respectively, and shows some oscillation structures. Moreover, the optical functions for the system have also a rich structure with the variation of field frequency. It may demonstrate that this transport dependence on the external field parameters can be used to give the energy spectra information of carbon nanotubes and to detect the high-frequency microwave irradiation.

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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