Dynamic Competition between Hubbard and Superexchange Interactions Selectively Localizes Electrons and Holes through Polarons
Creators
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1.
California Institute of Technology
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2.
Yonsei University
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3.
Lawrence Livermore National Laboratory
Abstract
Controlling the effects of photoexcited polarons in transition metal oxides can enable the long time-scale charge separation necessary for renewable energy applications and controlling new quantum phases through dynamically tunable electron–phonon coupling. In previously studied transition metal oxides, polaron formation is facilitated by a photoexcited ligand-to-metal charge transfer (LMCT). When the polaron is formed, oxygen atoms move away from iron centers, which increases carrier localization at the metal center and decreases charge hopping. Studies of yttrium iron garnet and erbium iron oxide have suggested that strong electron and spin correlations can modulate photoexcited polaron formation. To understand the interplay between strong spin and electronic correlations in highly polar materials, we studied gadolinium iron oxide (GdFeO3), which selectively forms photoexcited polarons through an Fe–O–Fe superexchange interaction. Excitation-wavelength-dependent transient extreme ultraviolet (XUV) spectroscopy selectively excites LMCT and metal-to-metal charge transfer (MMCT) transitions. The LMCT transition suppresses photoexcited polaron formation due to the balance between superexchange and Hubbard interactions, while MMCT transitions result in photoexcited polaron formation within 250 ± 40 fs. Ab initio theory demonstrates that electron and hole polarons localize on iron centers following MMCT. In addition to understanding how strong electronic and spin correlations can control strong electron–phonon coupling, these experiments separately measure electron and hole polaron interactions on neighboring metal centers for the first time, providing insight into a large range of charge-transfer and Mott–Hubbard insulators.
Copyright and License
© 2025 American Chemical Society.
Acknowledgement
The authors thank Professor Hanzhe Liu, Dr. Jonathan Michelsen, and Levi Palmer for guidance and MATLAB scripts for performing the OCEAN calculations. This material is based on work performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub, under award number DE-SC0021266. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC02-05CH11231 using NERSC award BES-ERCAP0024109. The computations presented here were, in part, conducted in the Resnick High Performance Computing Center, a facility supported by the Resnick Sustainability Institute at the California Institute of Technology. The ground-state optical absorption of GdFeO3 was collected at the Molecular Materials Research Center in the Beckman Institute of the California Institute of Technology. Fluorescence lifetime measurements were performed in the Caltech Biological Imaging Center, with the support of the Caltech Beckman Institute and the Arnold and Mabel Beckman Foundation. J.L.M. acknowledges support by the National Science Foundation Graduate Research Fellowship Program under grant no. 1745301. GdFeO3 synthesis and characterization carried out at Yonsei University was supported by the National Research Foundation of Korea (NRF) through grants NRF-2021R1A2C1006375 and NRF-2022R1A2C1006740. The work of J.B.V. was performed under the auspices of the US DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and supported by the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy (DOE), the Office of Energy Efficiency and Renewable Energy (EERE), and the Hydrogen and Fuel Cell Technologies Office (HFTO).
Supplemental Material
See attached.
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.4c16837.
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GdFeO3 characterization, detailed descriptions of the transient XUV spectrometer, and ab initio modeling; long time-scale XUV spectra and fitting of polaron shifts.
Files
ja4c16837_si_001.pdf
Additional details
Funding
- National Science Foundation
- Graduate Research Fellowship Program 1745301
- National Energy Research Scientific Computing Center
- DE-AC52-07NA27344
- Office of Basic Energy Sciences
- DE-SC0021266
- National Research Foundation of Korea
- NRF-2021R1A2C1006375
- National Research Foundation of Korea
- NRF-2022R1A2C1006740
- Resnick Sustainability Institute
- California Institute of Technology
- Lawrence Livermore National Laboratory
- DE-AC52-07NA27344
Dates
- Available
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2025-05-02Published online
Caltech Custom Metadata
- Caltech groups
- Division of Chemistry and Chemical Engineering (CCE)
- Publication Status
- Published