Coherent Dirac plasmons in topological insulators

Richarj Mondal, Akira Arai, Yuta Saito, Paul Fons, Alexander V. Kolobov, Junji Tominaga, Muneaki Hase

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


We explore the ultrafast reflectivity response from photo-generated coupled phonon-surface Dirac plasmons in Sb2Te3 topological insulators several quintuple layers thick. The transient coherent phonon spectra obtained at different time frames exhibit a Fano-like asymmetric line shape of the A1g2 mode, which is attributed to quantum interference between continuumlike coherent Dirac plasmons and phonons. By analyzing the time-dependent asymmetric line shape using the two-temperature model (TTM), it was determined that a Fano-like resonance persisted up to ≈1 ps after photo excitation with a relaxation profile dominated by Gaussian decay at ≤200 fs. The asymmetry parameter could be well described by the TTM for ≥200 fs, therefore suggesting the coherence time of the Dirac plasmon is ≈200 fs.

Original languageEnglish
Article number144306
JournalPhysical Review B
Issue number14
Publication statusPublished - 2018 Apr 24
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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