Rashba Spin Orbit Interaction and Birefringent Electron Optics in Graphene

TL;DR

This paper explores how Rashba spin-orbit interaction in graphene creates birefringent electron optics, enabling spin-selective focusing and complex caustics, with potential for measuring Rashba coupling strength.

Contribution

It introduces the concept of birefringent electron optics in graphene due to Rashba interaction, demonstrating spin-dependent focusing and caustic patterns.

Findings

Birefringence causes complex caustic patterns in graphene electron optics.

Spin-selective focusing can be achieved with a circular gate.

Rashba coupling strength can be measured via scanning probe experiments.

Abstract

Electron optics exploits the analogies between rays in geometrical optics and electron trajectories, leading to interesting insights and potential applications. Graphene, with its two-dimensionality and photon-like behavior of its charge carriers, is the perfect candidate for the exploitation of electron optics. We show that a circular gate-controlled region in the presence of Rashba spin-orbit interaction in graphene may indeed behave as a Veselago electronic lens but with two different indices of refraction. We demonstrate that this birefringence results in complex caustics patterns for a circular gate, selective focusing of different spins, and the possible direct measurement of the Rashba coupling strength in scanning probe experiments.