The great potential of Dirac electrons for plasmonics and photonics has been readily recognized after their discovery in graphene, followed by applications to smart optical devices. Dirac carriers are also found in topological insulators (TI) --quantum systems having an insulating gap in the bulk and intrinsic Dirac metallic states at the surface--. Here, we investigate the plasmonic response of ring structures patterned in Bi2Se3 TI films, which we investigate through terahertz (THz) spectroscopy. The rings are observed to exhibit a bonding and an antibonding plasmon modes, which we tune in frequency by varying their diameter. We develop an analytical theory based on the THz conductivity of unpatterned films, which accurately describes the strong plasmon-phonon hybridization and Fano interference experimentally observed as the bonding plasmon is swiped across the promineng 2\,THz phonon exhibited by this material. This work opens the road for the investigation of plasmons in topological insulators and for their application in tunable THz devices.
@article{arxiv.1504.02592,
title = {Plasmon-phonon interactions in topological insulator rings},
author = {Marta Autore and Fausto D'Apuzzo and Alessandra Di Gaspare and Valeria Giliberti and Odeta Limaj and Pascale Roy and Matthew Brahlek and Nikesh Koirala and Seongshik Oh and Francisco Javier Garcìa de Abajo and Stefano Lupi},
journal= {arXiv preprint arXiv:1504.02592},
year = {2015}
}
Comments
9 pages, 2 figures. To be published in Advanced Optical Materials