Gate tuneable beamsplitter in ballistic graphene

TL;DR

This paper demonstrates a gate-tunable beam splitter in ballistic graphene, where the p-n interface acts as a controllable semi-transparent mirror, enabling potential electron-optic interferometry.

Contribution

The work introduces a novel, tunable beam splitter in ballistic graphene using local gates to control the p-n interface's reflectance and position.

Findings

The p-n interface acts as a semi-transparent mirror in bipolar regime.

Reflectance and transmittance are tunable via gate voltages.

The p-n interface position can be shifted by approximately 1 micron.

Abstract

We present a beam splitter in a suspended, ballistic, multiterminal, bilayer graphene device. By using local bottomgates, a p-n interface tilted with respect to the current direction can be formed. We show that the p-n interface acts as a semi-transparent mirror in the bipolar regime and that the reflectance and transmittance of the p-n interface can be tuned by the gate voltages. Moreover, by studying the conductance features appearing in magnetic field, we demonstrate that the position of the p-n interface can be moved by $1\,\mu$m. The herein presented beamsplitter device can form the basis of electron-optic interferometers in graphene.