Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 25: Transport: Graphene
(Joint session of DS, DY, HL, MA, O and TT organized by TT)
MA 25.7: Vortrag
Mittwoch, 9. März 2016, 11:30–11:45, H22
Valley-based Cooper pair splitting via topologically confined channels in bilayer graphene — •Alexander Schroer1, Peter G. Silvestrov1, and Patrik Recher1,2 — 1Institut für Mathematische Physik, Technische Universität Braunschweig, D-38106 Braunschweig, Germany — 2Laboratory for Emerging Nanometrology Braunschweig, D-38106 Braunschweig, Germany
Bilayer graphene hosts valley-chiral one-dimensional modes at domain walls between regions of different interlayer potential or stacking order. When such a channel is close to a superconductor, the two electrons of a Cooper pair, which tunnel into it, move in opposite directions because they belong to different valleys related by the time-reversal symmetry. This kinetic variant of Cooper pair splitting requires neither Coulomb repulsion nor energy filtering but is enforced by the robustness of the valley isospin in the absence of atomic-scale defects. We derive an effective normal/superconducting/normal (NSN) model of the channel in proximity to an s-wave superconductor, calculate the conductance of split and spin-entangled pairs, and interpret it as a result of local Andreev reflection, in contrast to the widespread identification of Cooper pair splitting with crossed Andreev reflection in an NSN geometry.