Wen et al. demonstrate room-temperature ODMR in hot-pressed polycrystalline hBN; alignment-free scalar magnetometry under ambient conditions globally.

Room-temperature alignment-free magnetometry with boron vacancies in hot-pressed hexagonal boron nitride - Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf, HZDR

Room-temperature alignment-free magnetometry with boron vacancies in hot-pressed hexagonal boron nitride

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Wen, S. ; Coto, R.; Wen, P. ; Prucnal, S. ; Helm, M.; Luo, J.-W.; Zhou, S. ; Berencen, Y.

Magnetic-field sensing is essential for applications ranging from communication and environmental monitoring to biomedical diagnostics. Quantum sensors based on solid-state spin defects, such as nitrogen-vacancy centers in diamond and boron vacancies (VB-) in hexagonal boron nitride (hBN), typically require precise alignment between the external magnetic field and the defect spin quantization axis, limiting their practical deployment. Here, we demonstrate room-temperature optically detected magnetic resonance (ODMR) from negatively charged boron vacancies in commercially available hot-pressed polycrystalline hBN. The random orientation of crystallites gives rise to an ensemble of defect quantization axes, enabling magnetic-field detection without the need for precise sensor alignment. The resulting orientation-averaged ODMR response exhibits broadened linewidths and reduced contrast compared with single-crystal hBN, while retaining clear magnetic-field-dependent signatures. Numerical simulations incorporating hyperfine interactions, anisotropic broadening, and preferential defect alignment accurately reproduce the experimental ODMR spectra across different magnetic-field strengths and orientations. Although the ensemble response does not permit unambiguous reconstruction of the magnetic-field vector, it enables robust alignment-free (scalar) magnetometry under ambient conditions. These results establish hot-pressed polycrystalline hBN as a scalable platform for room-temperature quantum magnetic-field sensing and highlight the potential of disordered spin ensembles for practical quantum sensing applications.

Keywords: Optically active spin defects; hexagonal boron nitride; He irradiation; Optically detected magnetic resonance; Room-temperature magnetometry; Quantum sensing

Ion Beam Center DOI: 10.17815

jlsrf-3-159 is cited by this (Id 43749) publication

Communications Materials 7(2026), 209 DOI: 10.1038

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