Creating and Steering Highly Directional Electron Beams in Graphene

TL;DR

This paper proposes a novel method to generate and control highly directional, non-dispersive electron beams in graphene using a lens based on negative refraction and Klein collimation, enabling advanced electron optics experiments.

Contribution

It introduces a new lens design for graphene electron beams that maintains collimation over microns and can be steered magnetically, advancing electron optics technology.

Findings

Demonstrates high-resolution angle-dependent Klein tunneling observation.

Shows high-fidelity transverse magnetic focusing with simulations.

Proposes experimental setups for next-generation graphene electron optics.

Abstract

We put forward a concept to create highly collimated, non-dispersive electron beams in pseudo-relativistic Dirac materials such as graphene or topological insulator surfaces. Combining negative refraction and Klein collimation at a parabolic pn junction, the proposed lens generates beams, as narrow as the focal length, that stay focused over scales of several microns and can be steered by a magnetic field without losing collimation. We demonstrate the lens capabilities by applying it to two paradigmatic settings of graphene electron optics: We propose a setup for observing high-resolution angle-dependent Klein tunneling, and, exploiting the intimate quantum-to-classical correspondence of these focused electron waves, we consider high-fidelity transverse magnetic focusing accompanied by simulations for current mapping through scanning gate microscopy. Our proposal opens up new perspectives for next-generation graphene electron optics experiments.