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arXiv:2609.39535

Boron vacancies in bulk h-BN created by high-energy He+ irradiation

P. G. Vilyuzhanina, S. V. Bolshedvorskii, R. Isayev, A. S. Doroshkevich, A. A. Tatarinova, V. V. Soshenko, I. S. Cojocaru, A. M. Kozodaev, S. M. Drofa, A. Chernyavskiy, N. I. Salangin, A. N. Smolyaninov, A. Y. Kuntsevich, A. V. Akimov

quant-phcond-mat.mtrl-sciSubmitted Sep 30, 2026• Announced Oct 1, 2026
arXivHTMLPDF

Abstract

While color centers in diamond and other three-dimensional crystals are nowadays key elements of several types of sensors, color centers in two-dimensional materials are rapidly developing and promise high-tech applications. One of the interesting centers in 2D materials is the negatively charged boron vacancy in hexagonal boron nitride (h-BN), which has already shown some potential for magnetometry, but the reliable creation of boron vacancies remains challenging. Here, we demonstrate the fabrication of negatively charged boron vacancy color centers in bulk h-BN via implantation of helium ions at ~1 MeV, as confirmed by characteristic photoluminescence and optically detected magnetic resonance. The resonance has a width of 180 MHz and exhibits the expected Zeeman shift of the resonance lines. The depth of the color center along the c-axis of the h-BN crystal was measured and compared with predictions from Stopping and Range of Ions in Matter modeling. The experimental value and the modeled prediction are consistent within the reported uncertainties, as their 1σ intervals overlap, although the experiment shows a greater depth and a wider distribution.

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Boron vacancies ($V_B^-$) in hexagonal boron nitride (hBN) have emerged as a promising platform for two-dimensional quantum sensors capable of operating at atomic-scale proximity. However, the mechanisms responsible for photoluminescence quenching in thin hBN sensing layers when placed in contact with absorptive materials remain largely unexplored. In this Letter, we investigate non-radiative Förster resonance energy transfer (FRET) between $V_B^-$ centers and either monolayer graphene or 2D semiconductors. Strikingly, we find that the FRET rate is negligible for hBN sensing layers thicker than 3 nm, highlighting the potential of $V_B^-$ centers for integration into ultra-thin quantum sensors within van der Waals heterostructures. Furthermore, we experimentally extract the intrinsic radiative decay rate of $V_B^-$ defects.

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We report the results of high-energy (1.8 MeV) proton implantation in a type-Ib diamond.The focused ion beam was used to introduce vacancies in a 20 µm-deep layer with applied doses in the range of 10 13 to 10 16 ions/cm 2 .The sample was subsequently annealed in vacuum which resulted in migration of vacancies and their association with the nitrogen present in the diamond matrix.We studied properties of the formed nitrogen-vacancy centers with photoluminescence and optically detected magnetic resonance.The samples are aimed to be used in sensing applications, e.g., magnetometry and bio-magnetic imaging.

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Spin defects in two-dimensional materials hold significant potential for quantum information technologies and sensing applications. The negatively charged boron vacancy (VB-) in hexagonal boron nitride (hBN) has attracted considerable attention as a quantum sensor due to its demonstrated sensitivity to temperature, magnetic fields, and pressure.1 However, its applications have thus far been limited by inherently dim photoluminescence (PL). By fabricating a van der Waals heterostructure with a sensitizing donor layer, lead iodide (PbI2), we effectively enhance the PL intensity from the VB- by 5-45x, while maintaining compatibility with other heterostructures and vdW optoelectronic platforms. The type-I band alignment at the heterojunction enables efficient exciton migration while suppressing back-electron transfer, and the strong spectral overlap between the PbI2 emission and defect absorption supports efficient fluorescence resonance energy transfer. Ab initio density functional theory (DFT) predicts a photon-ratcheting mechanism that boosts absorption and emission while maintaining magnetic resonance (ODMR) contrast through minimal hybridization. Experimentally, the heterostructure exhibits enhanced continuous-wave ODMR sensitivity and functions as a precise probe of external magnetic fields. This work establishes a proof-of-concept for amplifying weak defect signals in nanomaterials, highlighting a new strategy for engineering their optical and magnetic responses.

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Boron nitride is a layered crystal whose properties depend on how its atomic sheets are stacked. Its negatively charged boron vacancy is a well-established magnetic defect that can be prepared and read out optically, but in the common hexagonal form it emits very little light, because the symmetry of the surrounding lattice forbids the relevant optical transition. Here we show, using first-principles calculations, that stacking the sheets in the rhombohedral sequence instead removes this restriction and increases the emitted intensity by one to two orders of magnitude, while the magnetic properties remain comparable or improve. We predict that the resulting emission is bright enough for a single defect to be addressed at room temperature, and that a sharp emission line, absent in the hexagonal form, should appear on cooling. Stacking order therefore acts as a design parameter for tailoring the quantum properties of defects embedded in layered materials.

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Spatially resolved quantum magnetometry and stray-field reconstruction of permalloy microdisks using boron-vacancy centers in hexagonal boron nitride

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Transferable hexagonal boron nitride (hBN) hosting negatively charged boron-vacancy (VB$^{-}$) spin defects offers a versatile platform for integrated quantum magnetometry, yet quantitative imaging of magnetic microstructures remains challenging. Here, we integrate a transferred hBN flake with a 4 $μ$m-diameter permalloy (Py = Ni${81}$Fe${19}$) microdisk and perform spatially resolved optically detected magnetic resonance measurements at room temperature. An applied in-plane magnetic field distorts the vortex-state magnetization, generating edge-localized magnetic surface charges and pronounced stray-field signatures at opposite disk edges. By referencing each pixel to its local zero-field splitting and correcting for a residual out-of-plane bias field, we quantitatively reconstruct the out-of-plane stray-field distribution, revealing peak fields of approximately 11.2 mT. An edge-charge model reproduces the spatial distribution and amplitude of the reconstructed field, linking the ODMR response to the field-driven evolution of the vortex state. These results establish transferred hBN VB$^{-}$ sensors for quantitative magnetometry of magnetic microstructures.

cond-mat.mes-hallCross-listedarXiv:2609.21630•Sep 21, 2026
While color centers in diamond and other three-dimensional crystals are nowadays key elements of several types of sensors, color centers in two-dimensional materials are rapidly developing and promise high-tech applications. One of the interesting centers in 2D materials is the negatively charged boron vacancy in hexagonal boron nitride (h-BN), which has already shown some potential for magnetometry, but the reliable creation of boron vacancies remains challenging. Here, we demonstrate the fabrication of negatively charged boron vacancy color centers in bulk h-BN via implantation of helium ions at ~1 MeV, as confirmed by characteristic photoluminescence and optically detected magnetic resonance. The resonance has a width of 180 MHz and exhibits the expected Zeeman shift of the resonance lines. The depth of the color center along the c-axis of the h-BN crystal was measured and compared with predictions from Stopping and Range of Ions in Matter modeling. The experimental value and the modeled prediction are consistent within the reported uncertainties, as their 1σ intervals overlap, although the experiment shows a greater depth and a wider distribution.
Boron vacancies (VB−V_B^-VB−​) in hexagonal boron nitride (hBN) have emerged as a promising platform for two-dimensional quantum sensors capable of operating at atomic-scale proximity. However, the mechanisms responsible for photoluminescence quenching in thin hBN sensing layers when placed in contact with absorptive materials remain largely unexplored. In this Letter, we investigate non-radiative Förster resonance energy transfer (FRET) between VB−V_B^-VB−​ centers and either monolayer graphene or 2D semiconductors. Strikingly, we find that the FRET rate is negligible for hBN sensing layers thicker than 3 nm, highlighting the potential of VB−V_B^-VB−​ centers for integration into ultra-thin quantum sensors within van der Waals heterostructures. Furthermore, we experimentally extract the intrinsic radiative decay rate of VB−V_B^-VB−​ defects.
We report the results of high-energy (1.8 MeV) proton implantation in a type-Ib diamond.The focused ion beam was used to introduce vacancies in a 20 µm-deep layer with applied doses in the range of 10 13 to 10 16 ions/cm 2 .The sample was subsequently annealed in vacuum which resulted in migration of vacancies and their association with the nitrogen present in the diamond matrix.We studied properties of the formed nitrogen-vacancy centers with photoluminescence and optically detected magnetic resonance.The samples are aimed to be used in sensing applications, e.g., magnetometry and bio-magnetic imaging.
Spin defects in two-dimensional materials hold significant potential for quantum information technologies and sensing applications. The negatively charged boron vacancy (VB-) in hexagonal boron nitride (hBN) has attracted considerable attention as a quantum sensor due to its demonstrated sensitivity to temperature, magnetic fields, and pressure.1 However, its applications have thus far been limited by inherently dim photoluminescence (PL). By fabricating a van der Waals heterostructure with a sensitizing donor layer, lead iodide (PbI2), we effectively enhance the PL intensity from the VB- by 5-45x, while maintaining compatibility with other heterostructures and vdW optoelectronic platforms. The type-I band alignment at the heterojunction enables efficient exciton migration while suppressing back-electron transfer, and the strong spectral overlap between the PbI2 emission and defect absorption supports efficient fluorescence resonance energy transfer. Ab initio density functional theory (DFT) predicts a photon-ratcheting mechanism that boosts absorption and emission while maintaining magnetic resonance (ODMR) contrast through minimal hybridization. Experimentally, the heterostructure exhibits enhanced continuous-wave ODMR sensitivity and functions as a precise probe of external magnetic fields. This work establishes a proof-of-concept for amplifying weak defect signals in nanomaterials, highlighting a new strategy for engineering their optical and magnetic responses.
Boron nitride is a layered crystal whose properties depend on how its atomic sheets are stacked. Its negatively charged boron vacancy is a well-established magnetic defect that can be prepared and read out optically, but in the common hexagonal form it emits very little light, because the symmetry of the surrounding lattice forbids the relevant optical transition. Here we show, using first-principles calculations, that stacking the sheets in the rhombohedral sequence instead removes this restriction and increases the emitted intensity by one to two orders of magnitude, while the magnetic properties remain comparable or improve. We predict that the resulting emission is bright enough for a single defect to be addressed at room temperature, and that a sharp emission line, absent in the hexagonal form, should appear on cooling. Stacking order therefore acts as a design parameter for tailoring the quantum properties of defects embedded in layered materials.
Precise control over the spatial distribution and charge state of nitrogen-vacancy (NV) centers in diamond is a key requirement for further advancing this platform in quantum sensing and photonic applications. Here, we investigate nitrogen ion implantation as a scalable method to engineer NV centers in bulk single-crystalline (SC) and a 5 μ m -thick polycrystalline (PC) diamond membrane. Nitrogen-doped regions (1–80 ppm) were fabricated using a 0.7 MeV ion beam and high-temperature annealing, with NV center formation verified by confocal fluorescence imaging and spectral analysis. In SC bulk diamond, we estimate the NV concentration from spectral analysis and model the fluorescence response as a function of implantation dose, capturing both the initial increase at low concentrations and a saturation behavior at higher doses due to quenching mechanisms. In contrast, PC diamond membranes show a weaker dependence at low implantation fluences, consistent with pre-existing nitrogen impurities, thus making a statistical model significantly more complex. The activation yield is found to be of order of 1%, which is lower than in N-rich diamond samples, as implanted N is predominantly interstitial. Photoluminescence spectroscopy indicates that NV 0 is the dominant charge state in both materials, with a laser-power-dependent redistribution between neutral and negative charge states. Optically detected magnetic resonance (ODMR) measurements in SC bulk diamond resolve the hyperfine structure and allow extraction of the dephasing time ( T 2 ∗ ), while in PC diamond membranes, where NV centers tend do form near the grain boundaries, the ODMR signals are observed but spectral resolution is currently limited by impurities, grain-dependent NV orientations, and photoluminescence background.
Transferable hexagonal boron nitride (hBN) hosting negatively charged boron-vacancy (VB−^{-}−) spin defects offers a versatile platform for integrated quantum magnetometry, yet quantitative imaging of magnetic microstructures remains challenging. Here, we integrate a transferred hBN flake with a 4 μμμm-diameter permalloy (Py = Ni81{81}81Fe19{19}19) microdisk and perform spatially resolved optically detected magnetic resonance measurements at room temperature. An applied in-plane magnetic field distorts the vortex-state magnetization, generating edge-localized magnetic surface charges and pronounced stray-field signatures at opposite disk edges. By referencing each pixel to its local zero-field splitting and correcting for a residual out-of-plane bias field, we quantitatively reconstruct the out-of-plane stray-field distribution, revealing peak fields of approximately 11.2 mT. An edge-charge model reproduces the spatial distribution and amplitude of the reconstructed field, linking the ODMR response to the field-driven evolution of the vortex state. These results establish transferred hBN VB−^{-}− sensors for quantitative magnetometry of magnetic microstructures.