Manifestation of Chiral tunneling at a tilted graphene p-n junction

Redwan N. Sajjad, S. Sutar, J. Lee and A. W. Ghosh, Physical Review B , 86 :155412 (2012).
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Electrons in graphene follow unconventional trajectories at p-n junctions, driven by their pseudospintronic degree of freedom. The prominent angular dependence of transmission is significant, capturing the chiral nature of the electrons and culminating in unit transmission at normal incidence (Klein tunneling). We theoretically show that such chiral tunneling can be directly observed from the junction resistance of a tilted interface probed with separate split gates. The junction resistance is shown to increase with tilt, in agreement with recent experimental evidence. The tilt dependence arises because of the misalignment between modal density and the anisotropic transmission lobe oriented perpendicular to the tilt. A critical determinant is the presence of specular edge scattering events that can completely reverse the angle dependence. The absence of such reversals in the experiments indicates that these edge effects are not overwhelmingly deleterious, making the premise of transport governed by electron “optics” in graphene an exciting possibility.