2 research outputs found
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Tuning and Persistent Switching of Graphene Plasmons on a Ferroelectric Substrate
We characterized plasmon propagation
in graphene on thin films of the high-κ dielectric PbZr<sub>0.3</sub>Ti<sub>0.7</sub>O<sub>3</sub> (PZT). Significant modulation
(up to ±75%) of the plasmon wavelength was achieved with application
of ultrasmall voltages (< ±1 V) across PZT. Analysis of the
observed plasmonic fringes at the graphene edge indicates that carriers
in graphene on PZT behave as noninteracting Dirac Fermions approximated
by a semiclassical Drude response, which may be attributed to strong
dielectric screening at the graphene/PZT interface. Additionally,
significant plasmon scattering occurs at the grain boundaries of PZT
from topographic and/or polarization induced graphene conductivity
variation in the interior of graphene, reducing the overall plasmon
propagation length. Lastly, through application of 2 V across PZT,
we demonstrate the capability to persistently modify the plasmonic
response of graphene through transient voltage application
Faraday Rotation Due to Surface States in the Topological Insulator (Bi<sub>1–<i>x</i></sub>Sb<sub><i>x</i></sub>)<sub>2</sub>Te<sub>3</sub>
Using
magneto-infrared spectroscopy, we have explored the charge dynamics
of (Bi,Sb)<sub>2</sub>Te<sub>3</sub> thin films on InP substrates.
From the magneto-transmission data we extracted three distinct cyclotron
resonance (CR) energies that are all apparent in the broad band Faraday
rotation (FR) spectra. This comprehensive FR-CR data set has allowed
us to isolate the response of the bulk states from the intrinsic surface
states associated with both the top and bottom surfaces of the film.
The FR data uncovered that electron- and hole-type Dirac Fermions
reside on opposite surfaces of our films, which paves the way for
observing many exotic quantum phenomena in topological insulators