Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 2: Nanotubes, Nanoribbons and Graphene
TT 2.8: Talk
Monday, September 5, 2022, 11:15–11:30, H22
Massless Dirac fermions with time-dependent magnetic barriers — •Nico Leumer1 and Wolfgang Häusler2 — 1IPCMS, CNRS, University of Strasbourg, France — 2University of Augsburg, Germany
Potential barriers controlled by gate electrodes, as common for 2D-electron gases, are inefficient to guide graphene carriers, due to the Klein tunneling phenomenon. One well known way out consists in using inhomogeneous magnetic fields [1]. However, when considering temporal variations, fundamental differences arise between electric and magnetic fields. While to good approximation the former can be treated on its own, time dependent magnetic fields always will induce electric fields of comparable strengths, according to Maxwell’s equations. Following Ref. [2] we report on the complete analytical solution for transmission through a weakly, ω-periodically modulated magnetic barrier, homogeneous along the y-direction, accounting for side bands that appear at energies E±ω in first order perturbation theory. Inherently, magnetic fields generalize the scattering problem to two dimensions. We find that sideband transport requires the static barrier to be permeable, while momentum conservation imposes new, independent conditions for complete reflection.
[1] A. De Martino, L. Dell’Anna, R. Egger, PRL 98, 066802 (2007)
[2] M. Büttiker, R. Landauer, PRL 49, 1739 (1982)