A tiny lateral shift of only about 0.01 nm between graphene layers can strongly affect electron transport, even though it does not change the thickness of the tunneling barrier. We reveal that this unexpected effect originates from changes in the quantum phase relationships of electron wave functions rather than from a simple change in tunneling distance.
More specifically, we study electron transmission through a monolayer/gapped bilayer/monolayer
graphene junction (MBMGJ), where a perpendicular electric field opens a gap in the bilayer region. We show that the shear displacement modifies the evanescent electron waves inside the gapped bilayer by changing the relative phase between wave functions on the two sublattices within each graphene layer of the bilayer, thereby modifying the conductance.
This mechanism also suggests a new electrical approach to probe atomic-scale interlayer shear vibrations: a pump laser pulse can excite the vibration, which periodically changes how easily electrons pass through the graphene junction. When this motion is combined with an oscillating electric field from a probe light, the phase difference between these two AC signals produces a measurable DC current. The proposed method could transform the otherwise difficult-to-detect effects of atomic-scale motion on electron transport into a measurable electrical signal.
Ryo Tamura, “Effects of shear displacement on the conductance of monolayer/gapped bilayer/monolayer graphene junctions: Implications for AC-DC conversion, Phys. Rev. B, in press.