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

Nature Physics (2025)Cite this article 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.This is a preview of subscription content, access via your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any timeSubscribe to this journal Receive 12 print issues and online access $259.00 per yearonly $21.58 per issueBuy this articlePrices may be subject to local taxes which are calculated during checkoutSource 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.Gottscholl, A. et al. 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Google Scholar Weigend, F. & Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: design and assessment of accuracy. Phys. Chem. Chem. Phys. 7, 3297 (2005).Article Google Scholar Perdew, J. P., Ernzerhof, M. & Burke, K. Rationale for mixing exact exchange with density functional approximations. J. Chem. Phys. 105, 9982 (1996).Article ADS Google Scholar Benedek, Z., Ganyecz, Á., Pershin, A., Ivády, V. & Barcza, G. Accurate and convergent energetics of color centers by wavefunction theory. Preprint at https://arxiv.org/abs/2406.05092 (2024).Download referencesThis 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.Department of Physics, School of Science, RMIT University, Melbourne, Victoria, AustraliaIslay O. Robertson, Sam C. Scholten, Priya Singh, Alexander J. Healey, Philipp Reineck, David A. Broadway & Jean-Philippe TetienneSchool of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, New South Wales, AustraliaBenjamin Whitefield, Mehran Kianinia & Igor AharonovichARC Centre of Excellence for Transformative Meta-Optical Systems, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, AustraliaBenjamin Whitefield, Mehran Kianinia & Igor AharonovichHUN-REN Wigner Research Centre for Physics, Budapest, HungaryGergely BarczaMTA-ELTE Lendület ‘Momentum’ NewQubit Research Group, Budapest, HungaryGergely Barcza & Viktor IvádyDepartment of Physics of Complex Systems, Eötvös Loránd University, Budapest, HungaryViktor IvádySearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarI.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.Correspondence to Igor Aharonovich or Jean-Philippe Tetienne.The authors declare no competing interests.Nature Physics thanks Yuan Ping, Chong Zu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.(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(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 dataDistribution G(u) of the monoexponential components of a stretched exponential function for selected values of the stretch exponent β.Source dataSupplementary Figs. 1–22, Tables 1–7 and discussion.Data for all plots in Fig. 1.Data for all plots in Fig. 2.Data for all plots in Fig. 3.Data for all plots in Fig. 4.Data for all plots in Fig. 6.Data for all plots in Extended Data Fig. 1.Data for all plots in Extended Data Fig. 2.Data for Extended Data Fig. 3.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsRobertson, I.O., Whitefield, B., Scholten, S.C. et al. A charge transfer mechanism for optically addressable solid-state spin pairs. Nat. Phys. (2025). https://doi.org/10.1038/s41567-025-03091-5Download citationReceived: 18 July 2024Accepted: 03 October 2025Published: 19 November 2025Version of record: 19 November 2025DOI: https://doi.org/10.1038/s41567-025-03091-5Anyone you share the following link with will be able to read this content:Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative