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arXiv 2109.08515physics.opticscond-mat.mtrl-sci
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拓扑绝缘体Bi $_2$ Se $_3$薄膜中的面内等离子体激元耦合

In-Plane Plasmon Coupling in Topological Insulator Bi$_2$Se$_3$ Thin Films

Saadia Nasir, Zhengtianye Wang, Sivakumar V. Mambakkam, Stephanie Law

摘要:

已知3D拓扑绝缘体(TI)Bi $_2$ Se $_3$的表面态在太赫兹光谱范围内具有二维狄拉克等离子体激元(DPP)。在TI薄膜中,在顶表面和底表面上激发的DPP耦合,导致声学和光学等离子体激元模式。因此,这些材料中的垂直耦合是合理的,但局部TI DPP之间的面内耦合还有待研究。在本文中,我们证明了在TI条形阵列的面内DPP耦合,并表明它们表现出偶极-偶极型耦合。耦合变得可忽略不计,其中晶格常数大于大约2.8倍的条纹宽度,这与在金属纳米颗粒或石墨烯等离子体激元上激发的局部等离子体激元的平面内耦合的结果相当。这种理解可以用于创建基于TI的元表面。

英文摘要:

The surface states of the 3D topological insulator (TI), Bi$_2$Se$_3$, are known to host two-dimensional Dirac plasmon polaritons (DPPs) in the terahertz spectral range. In TI thin films, the DPPs excited on the top and bottom surfaces couple, leading to an acoustic and an optical plasmon mode. Vertical coupling in these materials is therefore reasonable well-understood, but in-plane coupling among localized TI DPPs has yet to be investigated. In this paper, we demonstrate in-plane DPP coupling in TI stripe arrays and show that they exhibit dipole-dipole type coupling. The coupling becomes negligible with the lattice constant is greater than approximately 2.8 times the stripe width, which is comparable to results for in-plane coupling of localized plasmons excited on metallic nanoparticles or graphene plasmon polaritons. This understanding could be leveraged for the creation of TI-based metasurfaces.

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