Coupled Dirac Plasmons in Topological Insulators

Journal Article · 17 April 2018 · Advanced Optical Materials

DOI: https://doi.org/10.1002/adom.201800113 · OSTI ID:1593358

Ginley, Theresa P. ^[1]; Law, Stephanie ^[2]

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1. Univ. of Delaware, Newark, DE (United States). Dept. of Materials Science and Engineering; University of Delaware
2. Univ. of Delaware, Newark, DE (United States). Dept. of Materials Science and Engineering

Topological insulators are predicted to house spin-polarized two-dimensional Dirac plasmons. In topological insulator thin films, Dirac plasmons on the top and bottom surfaces will be coupled, giving rise to an unusual dispersion relationship. These plasmons are of interest both for fundamental science as well as applications in THz sensing and waveguiding. In this article, we present conclusive evidence for coupled Dirac plasmons excited in the surface states of topological insulator thin film stripe arrays by investigating how the plasmon frequency depends on both film thickness and stripe width. Bi₂Se₃ films of thickness 50-200nm are patterned into periodic stripes of width 1-4μm to excite plasmons. The plasmon frequency dependence on both film thickness and stripe width is found to be in good agreement with theoretical models for couple 2D Dirac plasmons. Alternative explanations such as 2D massive plasmons are shown to be inconstant with data. Finally, effective mode indexes of up to 211 are reported, demonstrating incredible confinement of light in the THz frequency range.

• Research Organization: Univ. of Delaware, Newark, DE (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: SC0017801
• OSTI ID: 1593358
• Journal Information: Advanced Optical Materials, Journal Name: Advanced Optical Materials Journal Issue: 13 Vol. 6; ISSN 2195-1071
• Publisher: WileyCopyright Statement
• Country of Publication: United States
• Language: English