Plasmon-enhanced near-field chirality in twisted van der Waals heterostructures

TL;DR

This paper demonstrates that twisted van der Waals heterostructures, like bilayer graphene, can generate highly chiral near-fields through plasmonic effects, enabling enantiomer-selective processes without external magnetic or patterning interventions.

Contribution

It introduces the concept of plasmon-enhanced near-field chirality in twisted heterostructures and estimates its magnitude compared to circularly polarized light.

Findings

Near-field chirality can be several orders of magnitude larger than circularly polarized light.

Chirality manifests as a deflection angle between plasmon propagation and Poynting vector.

Twisted heterostructures can facilitate enantiomer-selective processes without external magnetic fields.

Abstract

It is shown that chiral plasmons, characterized by a longitudinal magnetic moment accompanying the longitudinal charge plasmon, lead to electromagnetic near-fields that are also chiral. For twisted bilayer graphene, we estimate that the near field chirality of screened plasmons can be several orders of magnitude larger than that of the related circularly polarized light. The chirality also manifests itself in a deflection angle that is formed between the direction of the plasmon propagation and its Poynting vector. Twisted van der Waals heterostructures might thus provide a novel platform to promote enantiomer-selective physio-chemical processes in chiral molecules without the application of a magnetic field or external nano-patterning that break time-reversal, mirror plane or inversion symmetry, respectively.