Microwave-free imaging magnetometry with nitrogen-vacancy centers in nanodiamonds at near-zero field

Phys. Rev. Appl. 23, 034001 (2025) · DOI: 10.1103/PhysRevApplied.23.034001 · arXiv: 2409.02199

License: CC BY 4.0.

Abstract

Magnetometry using nitrogen-vacancy (N-V) color centers in diamond predominantly relies on microwave spectroscopy. However, microwaves may hinder certain studies involving biological systems or thin conductive samples. This work demonstrates a wide-field, microwave-free imaging magnetometer utilizing N-V centers in nanodiamonds by exploiting the cross-relaxation feature near zero magnetic fields under ambient conditions without applying microwaves. For this purpose, we measure the center shift, contrast, and linewidth of zero-field cross relaxation in 140-nm nanodiamonds dropcast on a current-carrying conductive pattern while scanning a background magnetic field, achieving a sensitivity of 4.5 μ T / Hz . Our work allows for applying the N-V zero-field feature in nanodiamonds for magnetic-field sensing in the zero- and low-field regimes and highlights the potential for microwave-free all-optical wide-field magnetometry based on nanodiamonds.

Figures

42 panels with data across 5 figures. Each panel page shows the plot, its columns and its files; each data.csv begins with a header naming the paper, the panel, the source, the license and the provenance route.

Fig. 1

• panel (e): Near-zero-field fluorescence spectrum of the nanodiamonds: normalized fluorescence against $B$ (mT), one curve. data.csv

Fig. 2

• panel (a-1): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0 A: the 0 A shift map of printed panel (a). The numbered pixel markers of the print are not drawn. data.csv
• panel (a-2): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 3 to 4 at 0 A: the 0 A contrast map of printed panel (a). data.csv
• panel (a-3): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0 A: the 0 A width map of printed panel (a). data.csv
• panel (a-4): Single-pixel zero-field spectrum 1 of printed panel (a), current path 3 to 4 at 0 A: normalized fluorescence against $B$ (mT) for the pixel marked 1 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (a-5): Single-pixel zero-field spectrum 2 of printed panel (a), current path 3 to 4 at 0 A: normalized fluorescence against $B$ (mT) for the pixel marked 2 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (a-6): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0.3 A: the 0.3 A shift map of printed panel (a). The numbered pixel markers of the print are not drawn. data.csv
• panel (a-7): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 3 to 4 at 0.3 A: the 0.3 A contrast map of printed panel (a). data.csv
• panel (a-8): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0.3 A: the 0.3 A width map of printed panel (a). data.csv
• panel (a-9): Single-pixel zero-field spectrum 3 of printed panel (a), current path 3 to 4 at 0.3 A: normalized fluorescence against $B$ (mT) for the pixel marked 3 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (a-10): Single-pixel zero-field spectrum 4 of printed panel (a), current path 3 to 4 at 0.3 A: normalized fluorescence against $B$ (mT) for the pixel marked 4 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (a-11): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0.5 A: the 0.5 A shift map of printed panel (a). The numbered pixel markers of the print are not drawn. data.csv
• panel (a-12): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 3 to 4 at 0.5 A: the 0.5 A contrast map of printed panel (a). data.csv
• panel (a-13): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 3 to 4 at 0.5 A: the 0.5 A width map of printed panel (a). data.csv
• panel (a-14): Single-pixel zero-field spectrum 5 of printed panel (a), current path 3 to 4 at 0.5 A: normalized fluorescence against $B$ (mT) for the pixel marked 5 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (a-15): Single-pixel zero-field spectrum 6 of printed panel (a), current path 3 to 4 at 0.5 A: normalized fluorescence against $B$ (mT) for the pixel marked 6 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-1): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0 A: the 0 A shift map of printed panel (b). The numbered pixel markers of the print are not drawn. data.csv
• panel (b-2): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 1 to 4 at 0 A: the 0 A contrast map of printed panel (b). data.csv
• panel (b-3): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0 A: the 0 A width map of printed panel (b). data.csv
• panel (b-4): Single-pixel zero-field spectrum 1 of printed panel (b), current path 1 to 4 at 0 A: normalized fluorescence against $B$ (mT) for the pixel marked 1 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-5): Single-pixel zero-field spectrum 2 of printed panel (b), current path 1 to 4 at 0 A: normalized fluorescence against $B$ (mT) for the pixel marked 2 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-6): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0.3 A: the 0.3 A shift map of printed panel (b). The numbered pixel markers of the print are not drawn. data.csv
• panel (b-7): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 1 to 4 at 0.3 A: the 0.3 A contrast map of printed panel (b). data.csv
• panel (b-8): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0.3 A: the 0.3 A width map of printed panel (b). data.csv
• panel (b-9): Single-pixel zero-field spectrum 3 of printed panel (b), current path 1 to 4 at 0.3 A: normalized fluorescence against $B$ (mT) for the pixel marked 3 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-10): Single-pixel zero-field spectrum 4 of printed panel (b), current path 1 to 4 at 0.3 A: normalized fluorescence against $B$ (mT) for the pixel marked 4 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-11): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0.5 A: the 0.5 A shift map of printed panel (b). The numbered pixel markers of the print are not drawn. data.csv
• panel (b-12): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m), current path 1 to 4 at 0.5 A: the 0.5 A contrast map of printed panel (b). data.csv
• panel (b-13): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m), current path 1 to 4 at 0.5 A: the 0.5 A width map of printed panel (b). data.csv
• panel (b-14): Single-pixel zero-field spectrum 5 of printed panel (b), current path 1 to 4 at 0.5 A: normalized fluorescence against $B$ (mT) for the pixel marked 5 in the shift map, left of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv
• panel (b-15): Single-pixel zero-field spectrum 6 of printed panel (b), current path 1 to 4 at 0.5 A: normalized fluorescence against $B$ (mT) for the pixel marked 6 in the shift map, right of the path. The black curve is a Lorentzian fit to the points and the dotted orange line marks zero field. data.csv

Fig. 3

• panel (1): Map of the zero-field-feature center shift $\Delta B$ (mT) over X and Y ($\mu$m) at 0.5 A, current path 3 to 4, the left map of the printed first row. The black horizontal line marks the pixel row of the line cuts below. data.csv
• panel (2): Map of the zero-field-feature contrast $C$ (%) over X and Y ($\mu$m) at 0.5 A, current path 3 to 4, the middle map of the printed first row. The black horizontal line marks the pixel row of the line cuts below. data.csv
• panel (3): Map of the zero-field-feature width $w$ (mT) over X and Y ($\mu$m) at 0.5 A, current path 3 to 4, the right map of the printed first row. The black horizontal line marks the pixel row of the line cuts below. data.csv
• panel (4): The $z$ component of the magnetic field, $B$ (mT), against X ($\mu$m) at 0.5 A along the pixel row marked by the black line in the maps above; the left plot of the printed second row. data.csv
• panel (5): Contrast of the zero-field feature against X ($\mu$m) at 0.5 A along the pixel row marked by the black line in the maps above; the middle plot of the printed second row. data.csv
• panel (6): Width of the zero-field feature, $B$ (mT), against X ($\mu$m) at 0.5 A along the pixel row marked by the black line in the maps above; the right plot of the printed second row. data.csv

Fig. 4

• panel (1): Zero-field-feature fit parameters measured close to the cross pattern against current (A): shift (circles) and FWHM (squares) on the left axis, magnetic field (mT), and contrast (diamonds) on the right axis (%). The solid curves are the trend lines drawn in the printed panel. data.csv

Fig. 5

• panel (a-1): Simulated magnetic field $B$ (mT) over X and Y ($\mu$m), 0.11 mm above the cross pattern with 0.5 A along current path 3 to 4. The black horizontal line marks the cut shown in panel a-2. data.csv
• panel (a-2): Components $B_x$, $B_y$ and $B_z$ of the simulated field, $B$ (mT), against X ($\mu$m) along the black line of panel a-1, current path 3 to 4 at 0.5 A. data.csv
• panel (b-1): Simulated magnetic field $B$ (mT) over X and Y ($\mu$m), 0.11 mm above the cross pattern with 0.5 A along current path 1 to 4. The black horizontal line marks the cut shown in panel b-2. data.csv
• panel (b-2): Components $B_x$, $B_y$ and $B_z$ of the simulated field, $B$ (mT), against X ($\mu$m) along the black line of panel b-1, current path 1 to 4 at 0.5 A. data.csv

Cite

Saravanan Sengottuvel, Omkar Dhungel, Mariusz Mrózek, Arne Wickenbrock, Dmitry Budker, Wojciech Gawlik, Adam M. Wojciechowski. Microwave-free imaging magnetometry with nitrogen-vacancy centers in nanodiamonds at near-zero field. Phys. Rev. Appl. 23, 034001 (2025). https://doi.org/10.1103/PhysRevApplied.23.034001

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