Strong interband Faraday rotation in 3D topological insulator Bi2Se3

Abstract

The recently emerged class of topological insulators (TIs)1–3 comprises materials with specific Dirac-type surface states, which continuously connect otherwise well-separated conduction and valence bands. The existence of these intriguing surface states is encoded in the specific bulk electronic band structures, which combines band inversion with time-reversal symmetry. The sensitivity to perturbations breaking the time-reversal symmetry makes TIs, and in particular their surface states, natural targets of Faraday rotation experiments4–7, allowing us, among other things, to trace the crossover from the topological to normal state of matter. Opening the band gap in the TI surface states should be, at subgap photon energies, manifested by a Faraday angle determined only by the fine structure constant α8,9. Other universal Faraday rotation effects have been proposed for Landau-quantized surface states of TIs10,11. These become analogous to predictions for other quantum Hall systems, including graphene and electron/hole gases in conventional 2D semiconductor heterostructures12, which have already been tested in the very first experiments13–15. In this paper, we report on a strong Faraday rotation in the well-known Bi2Se3 3D topological insulator. We show that the observed effect appears due to interband excitations in bulk, from the valence to the partially filled conduction band. The strength of the rotation, expressed in terms of the Verdet constant, is found to be extraordinary large for a non-magnetic material. This is related to the specific bulk electronic band structure of Bi2Se3, which implies that charge carriers closely resemble massive relativistic particles, with the spin-splitting large and equal for electrons and holes.

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Cite

BibTeX RIS

BibTeX

@article{ohnoutek2026strong,
  title = {{Strong interband Faraday rotation in 3D topological insulator Bi2Se3}},
  author = {L. Ohnoutek and M. Hakl and M. Veis and B. Piot and C. Faugeras and Gines Martinez Garcia and M. Yakushev and R. Martin and Č. Drašar and A. Materna and G. Strzelecka and A. Hruban and M. Potemski and M. Orlita},
  journal = {Scientific Reports},
  year = {2026},
  month = sep,
  doi = {10.1038/srep19087},
  eprint = {1512.00885},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-01986040v1},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - JOUR
TI  - Strong interband Faraday rotation in 3D topological insulator Bi2Se3
AU  - L. Ohnoutek
AU  - M. Hakl
AU  - M. Veis
AU  - B. Piot
AU  - C. Faugeras
AU  - Gines Martinez Garcia
AU  - M. Yakushev
AU  - R. Martin
AU  - Č. Drašar
AU  - A. Materna
AU  - G. Strzelecka
AU  - A. Hruban
AU  - M. Potemski
AU  - M. Orlita
PY  - 2026
DA  - 2026/09/23
JO  - Scientific Reports
DO  - 10.1038/srep19087
UR  - https://hal.science/hal-01986040v1
AB  - The recently emerged class of topological insulators (TIs)1–3 comprises materials with specific Dirac-type surface states, which continuously connect otherwise well-separated conduction and valence bands. The existence of these intriguing surface states is encoded in the specific bulk electronic band structures, which combines band inversion with time-reversal symmetry. The sensitivity to perturbations breaking the time-reversal symmetry makes TIs, and in particular their surface states, natural targets of Faraday rotation experiments4–7, allowing us, among other things, to trace the crossover from the topological to normal state of matter. Opening the band gap in the TI surface states should be, at subgap photon energies, manifested by a Faraday angle determined only by the fine structure constant α8,9. Other universal Faraday rotation effects have been proposed for Landau-quantized surface states of TIs10,11. These become analogous to predictions for other quantum Hall systems, including graphene and electron/hole gases in conventional 2D semiconductor heterostructures12, which have already been tested in the very first experiments13–15. In this paper, we report on a strong Faraday rotation in the well-known Bi2Se3 3D topological insulator. We show that the observed effect appears due to interband excitations in bulk, from the valence to the partially filled conduction band. The strength of the rotation, expressed in terms of the Verdet constant, is found to be extraordinary large for a non-magnetic material. This is related to the specific bulk electronic band structure of Bi2Se3, which implies that charge carriers closely resemble massive relativistic particles, with the spin-splitting large and equal for electrons and holes.
SN  - 2045-2322
ER  -

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