Observation of excitons bound by antiferromagnetic correlations
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1.
California Institute of Technology
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2.
SLAC National Accelerator Laboratory
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3.
University of California, Santa Barbara
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 Sr₂IrO₄ and Sr₃Ir₂O₇, we show using time-resolved THz spectroscopy that excitons exist only 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.
Copyright and License
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Acknowledgement
The authors thank Zala Lenarčič, Michael Buchhold, Eugene Demler and Victor Galitski for useful discussions. We thank S. J. Moon for sharing his equilibrium optical conductivity results. Terahertz spectroscopy measurements were supported by NSF Award No. DMR-2104833. D.H. acknowledges support for instrumentation from the Institute for Quantum Information and Matter (IQIM), an NSF Physics Frontiers Center (PHY-2317110). S.D.W. acknowledges partial support via NSF Award No. DMR-1729489. This work used facilities supported via the U.C. Santa Barbara NSF Quantum Foundry funded via the Q-AMASE-i program under Award No. DMR-1906325.
Supplemental Material
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Additional details
- National Science Foundation
- DMR-2104833
- National Science Foundation
- PHY-2317110
- National Science Foundation
- DMR-1729489
- National Science Foundation
- DMR-1906325
- Accepted
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2025-01-07
- Caltech groups
- Institute for Quantum Information and Matter
- Publication Status
- Published