Spin-Valley Beam Splitter in Graphene

TL;DR

This paper proposes a graphene-based device that spatially separates electron beams based on their spin and valley degrees of freedom, utilizing resonant tunneling and controllable parameters like gating and strain.

Contribution

It introduces a novel spin-valley beam splitter in graphene that leverages resonant tunneling and quasi-standing waves for effective beam separation.

Findings

Giant lateral Goos-H"{a}nchen shifts observed for all spin-valley components.

Resonant angles or energies differ for the four spin-valley flavors, enabling beam splitting.

Beam splitting can be controlled via gating and strain.

Abstract

The fourfold spin-valley degenerate degrees of freedom in bulk graphene can support rich physics and novel applications associated with multicomponent quantum Hall effects and linear conductance filtering. In this work, we study how to break the spin-valley degeneracy of electron beams spatially. We propose a spin-valley beam splitter in a gated ferromagnetic/pristine/strained graphene structure. We demonstrate that, in a full resonant tunneling regime for all spin-valley beam components, the formation of quasi-standing waves can lead four giant lateral Goos-H\"{a}nchen shifts as large as the transverse beam width, while the interplay of the two modulated regions can lead difference of resonant angles or energies for the four spin-valley flavors, manifesting an effective spin-valley beam splitting effect. The beam splitting effect is found to be controllable by the gating and strain.