1 research outputs found
Observation of Magnetoplasmons in Bi<sub>2</sub>Se<sub>3</sub> Topological Insulator
Both the collective (plasmon) and
the single particle (Drude) excitations
of an electron gas can be controlled and modified by an external magnetic
field <i>B</i>. At finite <i>B</i>, plasmon gives
rise to a magnetoplasmon mode and the Drude term to a cyclotron resonance.
These magnetic effects are expected to be extremely strong for Dirac
electrons with a linear energy-momentum dispersion, like those present
in graphene and topological insulators (TIs). Here, we investigate
both the plasmon and the Drude response versus <i>B</i> in
Bi<sub>2</sub>Se<sub>3</sub> topological insulator. At low <i>B</i>, the cyclotron resonance is still well separated in energy
from the magnetoplasmon mode; meanwhile, both excitations asymptotically
converge at the same energy for increasing <i>B</i>, consistently
with a dynamical mass for Dirac carriers of <i>m</i><sub>D</sub><sup>*</sup> = 0.18 ±
0.01 m<sub><i>e</i></sub>. In TIs, one then achieves an
excellent magnetic control of plasmonic excitations and this could
open the way toward plasmon controlled terahertz magneto-optics