Chirality probe of twisted bilayer graphene in the linear transport regime

TL;DR

This paper proposes minimal transport experiments with a third contact to detect the chirality of twisted bilayer graphene, revealing non-reciprocal transport and handedness-dependent voltage drops in the linear regime.

Contribution

It introduces a novel experimental setup using a third contact and magnetic fields to probe the chirality of twisted bilayer graphene in the linear transport regime.

Findings

Chiral systems show non-reciprocal transport with a third contact and magnetic field.

Opposite enantiomers produce different voltage drops on the third lead.

Chiral (super)currents can be induced without source-drain voltage in specific configurations.

Abstract

We propose minimal transport experiments in the coherent regime that can probe the chirality of twisted moir\'e structures. We show that only with a third contact and in the presence of an in-plane magnetic field (or other time-reversal symmetry breaking effect), a chiral system may display non-reciprocal transport in the linear regime. We then propose to use the third lead as a voltage probe and show that opposite enantiomers give rise to different voltage drops on the third lead. Additionally, in the scenario of layer-discriminating contacts, the third lead can serve as a current probe, capable of detecting different handedness even in the absence of a magnetic field. In a complementary configuration, applying opposite voltages on the two layers of the third leads gives rise to a chiral (super)current in the absence of a source-drain voltage whose direction is determined by its chirality.