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A charge transfer mechanism for optically addressable solid-state spin pairs

Nature Physics volume 21, pages 1981–1987 (2025)Cite this article

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Abstract

Bright point-defect emitters in hexagonal boron nitride have potential applications in quantum sensing and other technologies. However, it can be difficult to correctly identify the microscopic nature of observed defects, creating challenges for further development. A class of bright emitters exhibiting optically detected magnetic resonance with no resolvable zero-field splitting has been observed in hexagonal boron nitride across a broad range of wavelengths. However, the microscopic structure of the defects and the physical origin of their optically detected magnetic resonance signal have still not been identified. Here we describe a model that accounts for and provides a physical explanation for all key experimental features of the spin-resolved photodynamics of ensembles and single emitters. The model, inspired by the radical-pair mechanism from spin chemistry, assumes a pair of nearby point defects, one of which is optically active. Using first-principles calculations, we show that simple defect pairs made of common carbon defects provide a plausible realization of our model. As well as addressing open questions about defects in hexagonal boron nitride, our model may also explain similar phenomena observed in other wide-bandgap semiconductors.

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Fig. 1: Spin-active visible-band emitters in hBN.
Fig. 2: Spin-resolved photodynamics.
Fig. 3: Optical read-out of spin dynamics.
Fig. 4: PL settling-recovery dynamics.
Fig. 5: Proposed electronic structure.
Fig. 6: Microscopic modelling.

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Data availability

Source data are provided with this paper. All other data supporting the findings of this study are available within the paper and its Supplementary Information files.

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Acknowledgements

This work was supported by the Australian Research Council (grant nos. CE200100010, FT200100073, FT220100053, DE200100279, DP220100178, DE230100192 and DP250100973), the Office of Naval Research Global (grant no. N62909-22-1-2028) and the Air Force Office of Scientific Research (grant no. FA2386-25-1-4044). I.O.R. is supported by an Australian Government Research Training Program Scholarship. P.R. acknowledges support through an RMIT University Vice-Chancellor’s Research Fellowship. V.I. acknowledges support from the National Research, Development and Innovation Office of Hungary within the Quantum Information National Laboratory of Hungary (grant nos. 2022-2.1.1-NL-2022-00004 and FK145395). This project is funded by the European Union under Horizon Europe (projects 101156088 and 101129663). First-principles calculations were enabled by resources provided by the National Academic Infrastructure for Supercomputing in Sweden at the Swedish National Infrastructure for Computing at Tetralith, partially funded by the Swedish Research Council (grant agreement no. 2022-06725) and KIFÜ high-performance computation units in Hungary.

Author information

Authors and Affiliations

  1. Department of Physics, School of Science, RMIT University, Melbourne, Victoria, Australia

    Islay O. Robertson, Sam C. Scholten, Priya Singh, Alexander J. Healey, Philipp Reineck, David A. Broadway & Jean-Philippe Tetienne

  2. School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, New South Wales, Australia

    Benjamin Whitefield, Mehran Kianinia & Igor Aharonovich

  3. ARC Centre of Excellence for Transformative Meta-Optical Systems, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia

    Benjamin Whitefield, Mehran Kianinia & Igor Aharonovich

  4. HUN-REN Wigner Research Centre for Physics, Budapest, Hungary

    Gergely Barcza

  5. MTA-ELTE Lendület ‘Momentum’ NewQubit Research Group, Budapest, Hungary

    Gergely Barcza & Viktor Ivády

  6. Department of Physics of Complex Systems, Eötvös Loránd University, Budapest, Hungary

    Viktor Ivády

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  1. Islay O. Robertson
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Contributions

I.O.R., I.A. and J.-P.T. conceived of the project. I.O.R. and B.W. prepared the samples with assistance from A.J.H. and P.S. I.O.R., B.W. and P.R. built and performed the experiments with assistance from S.C.S., A.J.H. and M.K. I.O.R., S.C.S. and J.-P.T. performed the numerical simulations. G.B. and V.I. performed the ab initio calculations. D.A.B., I.A. and J.-P.T. supervised the project. All authors analysed the results and contributed to the writing of the paper.

Corresponding authors

Correspondence to Igor Aharonovich or Jean-Philippe Tetienne.

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Nature Physics thanks Yuan Ping, Chong Zu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Example PL images.

(a) Widefield PL image of the dense powder sample used for ensemble measurements. (b) Confocal PL map of the dilute powder sample used for measurements of single emitters. Grey circle indicates a single emitter.

Source data

Extended Data Fig. 2 Spin dynamics measurements.

(a) Rabi measurement pulse sequence indicating the front (F1, F2) and back (B1, B2) gated regions for PL averaging. (b) F1, F2 and B1, B2 plotted against τ. (c) T1 pulse sequence similarly with F1, F2 and B1, B2 marked on the laser pulses which are plotted against τ in (d). (e) Hahn echo pulse sequence with F1, F2 and B1, B2 marked on the laser pulses which are plotted against τ in (f). Inset: Normalised Hahn echo data fit with a single exponential.

Source data

Extended Data Fig. 3 Stretched exponential function.

Distribution G(u) of the monoexponential components of a stretched exponential function for selected values of the stretch exponent β.

Source data

Supplementary information

Supplementary Information

Supplementary Figs. 1–22, Tables 1–7 and discussion.

Source data

Source Data Fig. 1

Data for all plots in Fig. 1.

Source Data Fig. 2

Data for all plots in Fig. 2.

Source Data Fig. 3

Data for all plots in Fig. 3.

Source Data Fig. 4

Data for all plots in Fig. 4.

Source Data Fig. 6

Data for all plots in Fig. 6.

Source Data Extended Data Fig. 1

Data for all plots in Extended Data Fig. 1.

Source Data Extended Data Fig. 2

Data for all plots in Extended Data Fig. 2.

Source Data Extended Data Fig. 3

Data for Extended Data Fig. 3.

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Robertson, I.O., Whitefield, B., Scholten, S.C. et al. A charge transfer mechanism for optically addressable solid-state spin pairs. Nat. Phys. 21, 1981–1987 (2025). https://doi.org/10.1038/s41567-025-03091-5

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