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DS: Fachverband Dünne Schichten
DS 30: Transport: Graphene
(Joint session of DS, DY, HL, MA, O and TT, organized by TT)
DS 30.3: Talk
Wednesday, March 9, 2016, 10:15–10:30, H22
Dirac fermion wave packets in oscillating potential barriers — Walter Pötz1, Sergey E. Savel’ev2, Peter Hänggi3, and •Wolfgang Häusler3 — 1Karl Franzens Univ. Graz, Inst. Phys., A-8010 Graz, Austria — 2Department of Physics, Loughborough University, Loughborough LE11 3TU, United Kingdom — 3Institut für Physik, Univ. Augsburg, 86135 Augsburg, Germany
We integrate the time-dependent (2+1)D Dirac equation for
massless fermions in graphene or topological insulator surfaces.
A recently developed staggered-grid leap-frog scheme is employed
[1,2]. We consider an initial Gaussian wave packet which moves in
the x-direction towards a potential barrier that is homogeneous
along y and oscillates periodically in time. As for the
x-dependence, we investigate square-well, sinusoidal, and
linear-ramp potential profiles. Small transversal momentum
components ky of the wave packet were analyzed analytically
[3] and predicted to generate non-zero current densities jy,
even at normal incidence ky=0 [4]. These findings are
consistent with the present numerical studies of particle-,
current-, and spin-density. We also investigate massive fermions:
regarding some properties they resemble massless fermions,
regarding other properties, however, peculiar intrinsic
oscillations, reminiscent of Zitterbewegung, appear.
R. Hammer and W. Pötz, PRB 88, 235119 (2013)
R. Hammer et al., J. Comp. Phys. 265, 50 – 70 (2014)
S.E. Savel’ev, W. Häusler, and P. Hänggi, PRL 109, 226602 (2012)
S.E. Savel’ev, W. Häusler, and P. Hänggi, EPJB 86, 433 (2013).