Momentum-Locked Edge Excitons in 2D Molecular Crystals
Abstract
In molecular crystals, molecular excitations can hybridize into collective Frenkel excitons. Here we show that doubly degenerate excitations in planar two-dimensional molecular crystals generate excitonic bands with nontrivial momentum-resolved topological characteristics and edge states appearing only for selected crystallographic terminations. Using a model inspired by aggregates of zinc phthalocyanine molecules deposited on insulating surfaces, we demonstrate that the existence of edge excitons depends sensitively on the crystallographic orientation of the boundary and is governed by the Zak phase of the underlying bulk bands. The resulting edge states exhibit momentum-locked elliptical polarization textures originating from the internal structure of the molecular excitations, potentially enabling directional optical coupling and excitation transport. Our results establish a route toward topological and polarization-textured excitonic states in two-dimensional molecular materials.
Related
- Observation of pseudospin-locked chiral edge transport in gyromagnetic photonic crystals
- Topological Frenkel excitons in 2D molecular crystals
- Supersolid crystals of dipolar excitons in a lattice
- Momentum-selective graphene spectroscopy of moiré excitons
- Self-Trapping Enabled Highly Bright Momentum-Indirect Interlayer Excitons
BibTeX
@misc{nayak2026momentumlocked,
title = {{Momentum-Locked Edge Excitons in 2D Molecular Crystals}},
author = {Sidhartha Nayak and Alex Boeglin and Quentin Stein and Katharina Kaiser and Guillaume Schull and Thomas Frederiksen and Tomáš Neuman},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.09148},
eprint = {2610.09148},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.09148},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Momentum-Locked Edge Excitons in 2D Molecular Crystals
AU - Sidhartha Nayak
AU - Alex Boeglin
AU - Quentin Stein
AU - Katharina Kaiser
AU - Guillaume Schull
AU - Thomas Frederiksen
AU - Tomáš Neuman
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.09148
UR - https://arxiv.org/abs/2610.09148
AB - In molecular crystals, molecular excitations can hybridize into collective Frenkel excitons. Here we show that doubly degenerate excitations in planar two-dimensional molecular crystals generate excitonic bands with nontrivial momentum-resolved topological characteristics and edge states appearing only for selected crystallographic terminations. Using a model inspired by aggregates of zinc phthalocyanine molecules deposited on insulating surfaces, we demonstrate that the existence of edge excitons depends sensitively on the crystallographic orientation of the boundary and is governed by the Zak phase of the underlying bulk bands. The resulting edge states exhibit momentum-locked elliptical polarization textures originating from the internal structure of the molecular excitations, potentially enabling directional optical coupling and excitation transport. Our results establish a route toward topological and polarization-textured excitonic states in two-dimensional molecular materials.
ER -