Bosonic Delocalization of Dipolar Moiré Excitons

• Published in: arXiv.org
• Main Authors: Brem, Samuel, Malic, Ermin
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 01.06.2023
• Subjects: Density; Dipoles; Excitons; Interlayers; Lattices; Physics - Computational Physics; Physics - Materials Science; Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics; Superlattices; Transport properties; Trapping
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2306.00465

In superlattices of twisted semiconductor monolayers, tunable moiré potentials emerge, trapping excitons into periodic arrays. In particular, spatially separated interlayer excitons are subject to a deep potential landscape and they exhibit a permanent dipole providing a unique opportunity to study interacting bosonic lattices. Recent experiments have demonstrated density-dependent transport properties of moiré excitons, which could play a key role for technological applications. However, the intriguing interplay between exciton-exciton interactions and moiré trapping has not been well understood yet. In this work, we develop a microscopic theory of interacting excitons in external potentials allowing us to tackle this highly challenging problem. We find that interactions between moiré excitons lead to a delocalization at intermediate densities and we show how this transition can be tuned via twist angle and temperature. The delocalization is accompanied by a modification of optical moiré resonances, which gradually merge into a single free exciton peak. The predicted density-tunability of the supercell hopping can be utilized to control the energy transport in moiré materials.