Asymmetric transmission of electrons in ballistic graphene

Abstract

Semiconductor $p$-$n$ junctions with depletion zones have gained widespread use as a conventional way to give rise to electron asymmetric transmission. However, the approach is not applicable to monolayer graphene due to its characteristic feature of zero band gap. Asymmetric transmission in ballistic graphene therefore remains elusive to date. Here a simple approach based on the engineering of a four-layer array of quantum dots is proposed. Despite the array having few layers, it has the combined functionality of electron metasurfaces and band-gap materials with the symmetry breaking of spatial inversion, the extraordinary properties enabling electron asymmetric transmission. Our results open up the possibility of realizing electronic units dependent on the one-way effect and show great application potential with nearly perfect efficiency and simple design.