All-optical low-field magnetometry of superconductors using NV nanodiamonds

Measurement 283, 122080 (2026) · DOI: 10.1016/j.measurement.2026.122080 · arXiv: 2510.11920

License: CC BY 4.0.

Abstract

Nitrogen-vacancy centers in nanodiamond offer a microwave-free, noninvasive platform for probing superconductors via near zero-field cross-relaxation magnetometry. We demonstrate this by depositing nanodiamonds on YBa2Cu3O7-d thin films to measure critical parameters: transition temperature and penetration field. This method leverages nanodiamond fluorescence modulation as a result of magnetic field variation with 1 mT amplitude to observe the Meissner effect and field scans to measure the penetration field. The approach is minimally invasive and can be applied to superconducting samples with rough surfaces, facilitating the study of flux vortices and critical phenomena in complex geometries.

Figures

18 panels with data across 4 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

Illustrative figure, no extractable data. Shown in the paper PDF.

Fig. 2

• panel (a): Waterfall of the cross-relaxation feature of the nanodiamonds: PL (Norm.) against field (mT) at 15 temperatures from 5 K to 294 K, one curve each. The curves sit at equal steps along the temperature axis, as printed, although the temperatures are not equally spaced. data.csv
• panel (b-1): FWHM (mT) of the cross-relaxation feature against temperature (K), with error bars (the fitting errors, which are not purely statistical) and the linear FWHM fit. One of the three quantities of the printed triple-axis panel (B), split here into three panels; the gray band of the print is not drawn. data.csv
• panel (b-2): Contrast (%) of the cross-relaxation feature against temperature (K), with error bars (the fitting errors), none below 60 K, where the print hides them under the markers. One of the three quantities of the printed triple-axis panel (B), split here into three panels; the gray band of the print is not drawn. data.csv
• panel (b-3): Linewidth-to-contrast ratio, FWHM / Contrast, of the cross-relaxation feature against temperature (K), without error bars. One of the three quantities of the printed triple-axis panel (B), split here into three panels; the gray band of the print is not drawn. data.csv

Fig. 3

• panel (a): Lock-in amplifier output of the amplitude-modulated fluorescence signal against temperature (K): amplitude, Lock-in output Amp. (mV), on the left axis (voltage) and Lock-in output Phase (Degree) on the right axis (Phase). The Normal and Superconducting labels of the print are not drawn. data.csv
• panel (b): Derivative signal (mV/K), the rate of change $dR/dT$ of the lock-in signal, against temperature (K): Data and the double-Gaussian Fit, with green dashed lines at the two peaks, labelled 87.5 K and 88.2 K. The data are drawn as markers; the print draws them as a line. data.csv

Fig. 4

• panel (1): PL (Norm.) against field (mT) at the center of the superconductor at 110 K, two sweeps: Forward and Backward. The first of the six printed plots, in reading order. data.csv
• panel (2): PL (Norm.) against field (mT) at the center of the superconductor at 90 K, two sweeps: Forward and Backward. The second of the six printed plots, in reading order. data.csv
• panel (3): PL (Norm.) against field (mT) at the center of the superconductor at 88 K, two sweeps: Forward and Backward. The third of the six printed plots, in reading order. data.csv
• panel (4): PL (Norm.) against field (mT) at the center of the superconductor at 87 K, two sweeps: Forward and Backward. The fourth of the six printed plots, in reading order. data.csv
• panel (5): PL (Norm.) against field (mT) at the center of the superconductor at 85 K, two sweeps: Forward and Backward. The fifth of the six printed plots, in reading order. data.csv
• panel (6): PL (Norm.) against field (mT) at the center of the superconductor at 83 K, two sweeps: Forward and Backward. The sixth of the six printed plots, in reading order. data.csv

Fig. 5

• panel (1): PL (Norm.) against field (mT) at the edge of the superconductor at 90 K, two sweeps: Forward and Backward. The first of the six printed plots, in reading order. data.csv
• panel (2): PL (Norm.) against field (mT) at the edge of the superconductor at 88 K, two sweeps: Forward and Backward. The second of the six printed plots, in reading order. data.csv
• panel (3): PL (Norm.) against field (mT) at the edge of the superconductor at 85 K, two sweeps: Forward and Backward. The third of the six printed plots, in reading order. data.csv
• panel (4): PL (Norm.) against field (mT) at the edge of the superconductor at 80 K, two sweeps: Forward and Backward. The fourth of the six printed plots, in reading order. data.csv
• panel (5): PL (Norm.) against field (mT) at the edge of the superconductor at 65 K, two sweeps: Forward and Backward. The fifth of the six printed plots, in reading order. data.csv
• panel (6): PL (Norm.) against field (mT) at the edge of the superconductor at 5 K, two sweeps: Forward and Backward. The sixth of the six printed plots, in reading order. data.csv

Cite

Omkar Dhungel, Saravanan Sengottuvel, Mariusz Mrózek, Till Lenz, Nir Bar-Gill, Adam M. Wojciechowski, Arne Wickenbrock, Dmitry Budker. All-optical low-field magnetometry of superconductors using NV nanodiamonds. Measurement 283, 122080 (2026). https://doi.org/10.1016/j.measurement.2026.122080

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