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Josephson-like currents in graphene for arbitrary time-dependent potential barriers
journal contributionposted on 20.08.2015, 08:15 by Sergey Saveliev, Wolfgang Hausler, Peter Hanggi
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From the exact solution of the Dirac-Weyl equation we find unusual currents jy running in y-direction parallel to a time-dependent scalar potential barrier W(x, t) placed upon a monolayer of graphene, even for vanishing momentum component py. In their sine-like dependence on the phase difference of wave functions, describing left and right moving Dirac fermions, these currents resemble Josephson currents in superconductors, including the occurance of Shapiro steps at certain frequencies of potential oscillations. The Josephson-like currents are calculated for several specific time-dependent barriers. A novel type of resonance is discovered when, accounting for the Fermi velocity, temporal and spatial frequencies match.© EDP Sciences Società Italiana di Fisica Springer-Verlag 2013.
SES acknowledges support from the Alexander von Humboldt foundation through the Bessel prize and thanks Sasha Alexandrov and Viktor Kabanov for stimulating discussions. Also, SES was partially supported by Ministry of Science of Montenegro, under Contract No. 01-682. PH acknowledges the support by the German Excellence Initiative “Nanosystems Initiative Munich (NIM)”.