Nanosensor for weak magnetic fields based on the kramers degenerate spin system of Nanosensor for weak magnetic fields based on the kramers degenerate spin system of 14NV - 13C

In the past decade, magnetometry based on single nitrogen-vacancy ⁽¹⁴NV) color centers has become one of the most actively developed areas of quantum sensing [1–3]. An important challenge in ¹⁴NV-based magnetometry is accounting for internal crystal strain and associated electric fields E, which can significantly affect real diamond crystals. This makes it essential to separate magnetic and electric field contributions when interpreting optically detectable magnetic resonance spectra (ODMR) of ¹⁴NV centers used as sensors. One possible approach to address this problem is to employ Kramers-degenerate spin systems with half-integer spin [4].

In this work, we propose the use of a Kramers-degenerate spin system formed by a ¹⁴NV−¹³C complex as a nanoscale magnetic field sensor. Modeling based on the spin Hamiltonian shows that the lifting of the double degeneracy in this complex occurs solely due to the magnetic field and is unaffected by internal electric fields of the crystal, making it a promising candidate for precision magnetometry in electrically noisy environments. This complex was used to estimate the background magnetic field under laboratory conditions. Figure 1 shows a continuous-wave ODMR spectrum, where the resonance lines are split due to the presence of a magnetic field. This splitting reflects the component of the magnetic field along the quantization axis of the ¹⁴NV-¹³C complex. The measured value of this component is 40?µT, which is close to the strength of the Earth's magnetic field.

Figure 1. ODMR spectrum of the ¹⁴NV–¹³C complex in the presence of the laboratory's ambient magnetic field

The obtained results demonstrate the high potential of the ¹⁴NV–¹³C complex in the field of quantum magnetometry. Thanks to its nanometer-scale spatial resolution, provided by spin localization at the atomic level, this complex is capable of detecting magnetic fields with high precision and sensitivity. Furthermore, its robustness against internal electric disturbances, ensured by Kramers degeneracy, significantly enhances the reliability and selectivity of measurements in real crystals with inhomogeneous strain and noise. The combination of these properties opens up prospects for the development of a new generation of highly sensitive quantum sensors suitable for measuring weak magnetic fields with nanometer-scale spatial resolution across a wide range of scientific and applied fields.

Acknowledgments:

          This research was supported by the grant of Ministry of Science and Higher Education of Russian Federation No. 075-15-2024-556.

References:

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4. A. P. Nizovtsev,S. Ya. Kilin, A. L. Pushkarchuk, V. L. Pushkarchuk, S. A. Kuten, Nonlinear Phenomena in Complex Systems, 14 (4), 319 (2011).

In 1979, he graduated from Mordovia State University named after N.P. Ogarev, Faculty of Physics.In 1984, he completed postgraduate studies at Leningrad State University named after A.A. Zhdanov and was awarded the degree of Candidate of Physical and Mathematical Sciences. In 1990, he was awarded the academic title of Associate Professor. In 1998, he was awarded the degree of Doctor of Technical Sciences. In 1999, he was awarded the academic title of Professor. The main areas of scientific research are the physics and technology of wide-bandgap semiconductors.