Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 14: Graphene
TT 14.11: Vortrag
Montag, 1. April 2019, 18:00–18:15, H22
PN junctions in twisted bilayer graphene — •Christophe De Beule1 and Patrik Recher1,2 — 1Institute for Mathematical Physics, TU Braunschweig — 2Laboratory for Emerging Nanometrology, Braunschweig
We consider Andreev reflection at a normal-superconducting interface in twisted bilayer graphene where superconductivity is introduced via proximity effect, for twist angles in the range where both valley coupling and localization are weak. Due to the anisotropic band structure, the conductance depends strongly on the orientation of the tunneling junction with respect to the twisted bilayer graphene when the Fermi energy is near the Van Hove singularity. This can be understood from the opening of a scattering channel between parts of the Fermi surface that are localized in different layers. Moreover, Andreev (normal) reflection in this interlayer channel can be specular (retroreflective) even at Fermi energies much larger than the superconducting gap.