BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Avik Ghosh\, University of Virginia\n\nA major motivation for g raphene based electronics lies in its photon-like bandstructure\, which ma kes the electron effective mass vanishingly small and mobilities much larg er than their silicon counterparts. In practice however\, charge puddles w ash out the Dirac points and produce quasi-Ohmic current-voltage character istics\, making it hard to switch graphene electrons or to saturate their currents. Long channel devices saturate through remote optical phonon scat tering\, but are almost immediately compromised by band-to-band tunneling. One can \nopen a band-gap using quantization (e.g. nanoribbons)\, local s trains\, antidot arrays or transverse fields in bilayer geometries. But th e \nbroken symmetry invariably increases the mass of the electrons and com promises mobility. This trade-off seems fundamental. \n
\nThe richness o f graphene electronics lies not just in its photon like eigenspectrum\, bu t in the symmetry of its eigenvalues\, specifically\, the pseudospins aris ing from its dimer basis sets. On the one hand quasi-momentum conservation at a PN junction generates electronic analogues of Snell's law such as fo cusing\, total internal\nreflection\, and even negative index Veselago 'le nsing'. On the other hand\, the orthogonality of its pseudospins leads to Klein/antiKlein tunneling in mono/bilayer graphene\, for which there seem to be experimental evidence in close agreement with atomistic models for c urrent flow. By solving the Landauer-Keldysh quantum kinetic \nequations\, we show that such electron 'optics' and Klein tunneling can be used to de sign novel low power switches that can beat the Landauer-\nBoltzmann therm al limit\, including reconfigurable logic\, metal-insulator transition swi tches\, electron collimators and pseudospintronic analogs \nof electro-opt ic modulators. DTSTART:20121101T193000Z LOCATION:Physics Building\, Room 204 SUMMARY:Unconventional 'optics' with pseudospins in graphene: Metamaterial s\, Klein Tunneling and Subthermal switching END:VEVENT END:VCALENDAR