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arXiv 1401.4411cond-mat.str-elcond-mat.mes-hall
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拓扑绝缘体薄膜中的无带隙手征激子

Gapless chiral excitons in thin films of topological insulators

S. A. Jafari

摘要:

在强拓扑绝缘体(TI)的纳米级薄膜中,在板的两个不同平面中交换具有相同手性的两个电子的沟道中的库仑相互作用利用了由这种“交换”产生的负号,并且在一个表面中的正能态和相对表面中的负能态之间产生束缚态。因此,在TI薄膜的{ \em未掺杂}狄拉克锥中的粒子和空穴对形成位于自由粒子-空穴对的连续体下方的表面间自旋单重态。这种模式类似于半导体的激子,尽管形成于来自两个不同二维表面的电子和空穴对之间。对于低动量的色散关系表征这种集体模式是线性的。两个不同厚度的板的实验比较可以捕捉到本效应对板厚度的指数依赖性。

英文摘要:

In a nanoscopic thin film of a strong topological insulator (TI) the Coulomb interaction in the channel that exchanges the two electrons with the same chirality in two different planes of the slab takes advantage of the minus sign resulting from such "exchange" and gives rise to a bound state between the positive energy states in one surface and the negative energy states in the opposite surfaces. Therefore particle and hole pairs in the {\em undoped} Dirac cone of the TI thin film form an inter-surface spin-singlet state that lies below the continuum of free particle-hole pairs. This mode is similar to the excitons of semiconductors, albeit formed between the electron and hole pairs from two different two-dimensional surfaces. For low-momenta the dispersion relation characterizing this collective mode is linear. Experimental comparison of two slabs with different thicknesses can capture the exponential dependence of the present effect on the slab thickness.

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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