Valley splitter and transverse valley focusing in twisted bilayer graphene

authored by

Christophe De Beule, Peter G. Silvestrov, Ming Hao Liu, Patrik Recher

Abstract

We study transport in twisted bilayer graphene and show that electrostatic barriers can act as valley splitters, where electrons from the K (K′) valley are transmitted only to, e.g., the top (bottom) layer, leading to valley-layer locked currents. We show that such a valley splitter is obtained when the barrier varies slowly on the moiré scale and induces a Lifshitz transition across the junction, i.e., a change in the Fermi-surface topology. Furthermore, we show that for a given valley the reflected and transmitted current are transversely deflected, as time-reversal symmetry is effectively broken in each valley separately, resulting in valley-selective transverse focusing at zero magnetic field.

External Organisation(s)

Technische Universität Braunschweig
National Cheng Kung University
Laboratory for Emerging Nanometrology Braunschweig (LENA)

Type

Article

Journal

Physical Review Research

Volume

2

ISSN

2643-1564

Publication date

28.10.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Physics and Astronomy(all)

Electronic version(s)

https://doi.org/10.1103/PhysRevResearch.2.043151 (Access: Open)