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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: Vortrag

Dienstag, 17. März 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 Recher^1,3 — 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.