Strain controlled valley filtering in multi-terminal graphene structures

TL;DR

This paper demonstrates how local strain in multi-terminal graphene devices can generate valley-polarized currents, with optimal filtering achieved through specific bump geometries, and highlights the role of multiple sub-bands in enhancing current polarization.

Contribution

It introduces a method for strain-controlled valley filtering in graphene, emphasizing the importance of bump geometry and sub-band contributions for effective valley polarization.

Findings

Valley filtering is most effective with specific bump heights and widths.

Electrons from the lowest sub-band dominate the polarized current.

Higher sub-bands can significantly enhance the output current.

Abstract

Valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by the deformation allows electrons from only one valley to transmit and a current of electrons from a single valley is generated at the opposite side of the locally strained region. We show that valley filtering is most effective with bumps of a certain height and width. Despite the fact that the highest contribution to the polarized current comes from electrons from the lowest sub-band, contributions of other sub-bands are not negligible and can significantly enhance the output current.