Real-space nanoimaging of THz polaritons in the topological insulator Bi2Se3

Shu Chen, Andrei Bylinkin, Zhengtianye Wang, Martin Schnell, Greeshma Chandan, Peining Li, Alexey Y. Nikitin, Stephanie Law, Rainer Hillenbrand

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Plasmon polaritons in topological insulators attract attention from a fundamental perspective and for potential THz photonic applications. Although polaritons have been observed by THz far-field spectroscopy on topological insulator microstructures, real-space imaging of propagating THz polaritons has been elusive so far. Here, we show spectroscopic THz near-field images of thin Bi2Se3 layers (prototypical topological insulators) revealing polaritons with up to 12 times increased momenta as compared to photons of the same energy and decay times of about 0.48 ps, yet short propagation lengths. From the images we determine and analyze the polariton dispersion, showing that the polaritons can be explained by the coupling of THz radiation to various combinations of Dirac and massive carriers at the Bi2Se3 surfaces, massive bulk carriers and optical phonons. Our work provides critical insights into the nature of THz polaritons in topological insulators and establishes instrumentation and methodology for imaging of THz polaritons.

Original languageEnglish (US)
Article number1374
JournalNature communications
Volume13
Issue number1
DOIs
StatePublished - Dec 2022

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy

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