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Valley splitter and transverse valley focusing in twisted bilayer graphene

Authors :
Patrik Recher
Peter G. Silvestrov
Ming-Hao Liu (劉明豪)
Christophe De Beule
Source :
Physical Review Research. 2
Publication Year :
2020
Publisher :
American Physical Society (APS), 2020.

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 moir\'e 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.<br />Comment: 13 pages, 13 figures

Details

ISSN :
26431564
Volume :
2
Database :
OpenAIRE
Journal :
Physical Review Research
Accession number :
edsair.doi.dedup.....bbdf373ea99a7ee70c51de8229f2feb8
Full Text :
https://doi.org/10.1103/physrevresearch.2.043151