Brian Chapler

Voltage switching of a VO2 memory metasurface using ionic gel

We demonstrate an electrolyte-based voltage tunable vanadium dioxide (VO2) memory metasurface. Large spatial scale, low voltage, non-volatile switching of terahertz (THz) metasurface resonances is achieved through voltage application using an ionic gel to drive the insulator-to-metal transition in an underlying VO2 layer. Positive and negative voltage application can selectively tune the metasurface resonance into the “off” or “on” state by pushing the VO2 into a more conductive or insulating regime respectively. Compared to graphene based control devices, the relatively long saturation time of resonance modification in VO2 based devices suggests that this voltage-induced switching originates primarily from electrochemical effects related to oxygen migration across the electrolyte–VO2 interface.

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 PbZr0.3Ti0.7O3 (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.

Ferromagnetism and infrared electrodynamics of Ga1-xMnxAs

We report on the magnetic and the electronic properties of the prototype dilute magnetic semiconductor Ga

Infrared probe of the insulator-to-metal transition in Ga1−xMnxAs and Ga1−xBexAs

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Sum-rule constraints on the surface state conductance of topological insulators.

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Infrared nanospectroscopy and imaging of collective superfluid excitations in anisotropic superconductors

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Infrared conductivity of hole accumulation and depletion layers in (Ga,Mn)As- and (Ga,Be)As-based electric field-effect devices

As using infrared (IR) spectroscopy. Trends in the ferromagnetic transition temperature

Publisher's Note: Landau level spectroscopy of surface states in the topological insulator Bi0.91Sb0.09via magneto-optics [Phys. Rev. B85, 195440 (2012)]

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Optical study of strained ultrathin films of strongly correlated LaNiO3

with respect to the IR spectral weight are examined using a sum-rule analysis of IR conductivity spectra. We find non-monotonic behavior of trends in

Landau level spectroscopy of surface states in the topological insulator Bi0.91Sb0.09via magneto-optics

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