Ultrafast exciton transport in van der Waals heterostructures

TL;DR

This paper proposes an alternative model for ultrafast exciton transport in van der Waals heterostructures, suggesting waveguide modes and radiation transfer as key mechanisms, challenging previous interpretations of exciton propagation.

Contribution

It introduces a new waveguide mode-based model for exciton transport, providing a different explanation for ultrafast propagation observed in experiments.

Findings

Waveguide modes can facilitate ultrafast exciton transport.

The model explains nondiffusive propagation without collective effects.

Alternative interpretation challenges previous collective exciton theories.

Abstract

Excitons in van der Waals heterostructures based on atomically thin transition metal dichalcogenides are considered as potential candidates for the formation of a superfluid state in two-dimensional systems. A number of studies reported observations of ultrafast nondiffusive propagation of excitons in van der Waals heterostructures, which was considered by their authors as possible evidence of collective effects in excitonic systems. In this paper, after a brief analysis of exciton propagation regimes in two-dimensional semiconductors, an alternative model of ultrafast exciton transport is proposed, based on the formation of waveguide modes in van der Waals heterostructures and the radiation transfer by these modes.