Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 32: Twisted Bilayer Graphene (jointly with DY, MA, HL, DS, O) (joint session TT/HL)
HL 32.1: Talk
Tuesday, March 17, 2020, 14:00–14:15, HSZ 201
Valley splitter and transverse valley focusing in twisted bilayer graphene — •Christophe De Beule1, Peter Silvestrov1, Ming-Hao Liu2, and Patrik Recher1,3 — 1Institute for Mathematical Physics, TU Braunschweig, 38106 Braunschweig, Germany — 2Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan — 3Laboratory for Emerging Nanometrology, 38106 Braunschweig, Germany
We study transport through electrostatic barriers in twisted bilayer graphene and show that for certain configurations, electrons from the K (K') valley are transmitted only to the top (bottom) layer, leading to valley-layer locked bulk currents. We show that such a valley splitter is obtained when the potential varies slowly on the Moiré scale and the Fermi energy in the barrier exceeds the kinematic barrier between Dirac electrons from the top and bottom layer. Furthermore, we show that for a given valley the current is transversely deflected, as time-reversal symmetry is broken in each valley separately, resulting in valley-selective transverse focusing at zero magnetic field.