Strong nonlinear terahertz response induced by Dirac surface states in Bi2Se3 topological insulator.
Electrons with a linear energy/momentum dispersion are called massless Dirac electrons and represent the low-energy excitations in exotic materials such as graphene and topological insulators. Dirac electrons are characterized by notable properties such as a high mobility, a tunable density and, in topological insulators, a protection against backscattering through the spin-momentum locking mechanism. All those properties make graphene and topological insulators appealing for plasmonics applications. However, Dirac electrons are expected to present also a strong nonlinear optical behaviour. This should mirror in phenomena such as electromagnetic-induced transparency and harmonic generation. Here we demonstrate that in Bi2Se3 topological insulator, an electromagnetic-induced transparency is achieved under the application of a strong terahertz electric field. This effect, concomitantly determined by harmonic generation and charge-mobility reduction, is exclusively related to the presence of Dirac electron at the surface of Bi2Se3, and opens the road towards tunable terahertz nonlinear optical devices based on topological insulator materials.
INFN and Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Roma, Italy.
Flavio
F
Giorgianni
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Enrica
E
Chiadroni
INFN and Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Roma, Italy.
Andrea
A
Rovere
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Mariangela
M
Cestelli-Guidi
INSTM Udr Trieste-ST and Elettra-Sincrotrone Trieste S.C.p.A, Area Science Park, I-34012 Trieste, Italy.
Andrea
A
Perucchi
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Marco
M
Bellaveglia
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Michele
M
Castellano
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Domenico
D
Di Giovenale
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Giampiero
G
Di Pirro
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Massimo
M
Ferrario
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Riccardo
R
Pompili
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Cristina
C
Vaccarezza
Laboratori Nazionali di Frascati-INFN, Via E. Fermi, 40, I-00044 Frascati, Italy.
Fabio
F
Villa
INFN and Dipartimento di Fisica, Università di Roma 'Tor Vergata', viale della Ricerca Scientifica 1, I-00133 Roma, Italy.
Alessandro
A
Cianchi
INFN and Dipartimento S.B.A.I., Università di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Roma, Italy.
Andrea
A
Mostacci
INFN and Dipartimento S.B.A.I., Università di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Roma, Italy.
Massimo
M
Petrarca
Department of Physics and Astronomy Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019, USA.
Matthew
M
Brahlek
Department of Physics and Astronomy Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019, USA.
Nikesh
N
Koirala
Department of Physics and Astronomy Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019, USA.
Seongshik
S
Oh
INFN and Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Roma, Italy.
Stefano
S
Lupi