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arXiv · 2505.05565

Observation of excitons bound by antiferromagnetic correlations

Omar Mehio·Yuchen Han·Xinwei Li·Honglie Ning·Zach Porter·Stephen D. Wilson·David Hsieh
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Abstract

Two-dimensional Mott insulators host antiferromagnetic (AFM) correlations that are predicted to enhance the attractive interaction between empty (holons) and doubly occupied (doublons) sites, creating a novel pathway for exciton formation. However, experimental confirmation of this spin-mediated binding mechanism remains elusive. Leveraging the distinct magnetic critical properties of the Mott antiferromagnets Sr$_2$IrO$_4$ and Sr$_3$Ir$_2$O$_7$, we show using time-resolved THz spectroscopy that excitons only exist at temperatures below where short-range AFM correlation develops. The excitons remain stable up to photodoping densities approaching the predicted excitonic Mott insulator-to-metal transition, revealing a unique robustness against screening. Our results establish the viability of spin-bound excitons and introduce opportunities for excitonic control through magnetic degrees of freedom.

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Omar Mehio, Yuchen Han, Xinwei Li, Honglie Ning, Zach Porter, Stephen D. Wilson, David Hsieh. 2025-05-08. Observation of excitons bound by antiferromagnetic correlations. https://doi.org/10.1103/physrevresearch.7.013114

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