Transmission through a boundary between monolayer and bilayer graphene

TL;DR

This paper theoretically investigates electron transmission at the boundary between monolayer and bilayer graphene, revealing angle-dependent transmission and valley polarization effects due to evanescent waves.

Contribution

It introduces a detailed analysis of boundary transmission in graphene, highlighting valley polarization and the role of evanescent waves, which was not previously characterized.

Findings

Transmission depends strongly on incident angle.

Opposite dependence at K and K' points causes valley polarization.

Evanescent waves facilitate mode connection across the boundary.

Abstract

The electron transmission between monolayer and bilayer graphene is theoretically studied for zigzag and armchair boundaries within an effective-mass scheme. Due to the presence of an evanescent wave in the bilayer graphene, traveling modes are well connected to each other. The transmission through the boundary is strongly dependent on the incident angle and the dependence is opposite between the K and K' points, leading to valley polarization of transmitted wave.