MEPhI: Method of increasing the sensitivity of magnetic field sensors

2024: Introduction of a method to improve the sensitivity of magnetic field sensors

MEPhI has developed a method for increasing the sensitivity of magnetic field sensors. The university announced this on October 4, 2024.

source = MEPhI

Among the methods used for measuring the magnetic field for October 2024, magnetometry based on the so-called NV centers in diamond is very promising.

The NV center (English nitrogen-vacation center) or the nitrogen-replaced vacancy in diamond is a type of point defect in diamond: a violation of the structure of the crystal lattice of diamond, which occurs when the carbon atom is removed from the lattice node and the resulting vacancy is bound to the nitrogen atom. The peculiarity of the defect is that its properties are almost similar to those of an atom, be it "frozen" in the crystal lattice of a diamond: the electronic spins of an individual center are easily manipulated: light; magnetic, electric and microwave fields; this property of "defective diamonds" makes it the basis for creating sensors - in particular, magnetic field sensors.

One of the problems of NV center-based magnetometry in diamond is the need to take into account the effect on the NV centers of the intracrystalline field, which in real diamond crystals can be quite strong due to the presence of defects in the crystal structure. This can distort the sensor reading. In this regard, the problem of distinguishing the contributions of magnetic and electric fields when measuring the magnetic field is urgent. To solve this problem, scientists from NRNU MEPhI proposed replacing nitrogen isotopes when creating the NV center, or even using carbon instead of nitrogen.

If, instead of the nitrogen isotope, the 14N included in the NV center uses the 15N isotope or the NV center with a nearby 13S isotope in the crystal lattice of the diamond, then according to the calculations given, these hybrid quantum systems allow you to separate the effects from the intracrystalline fields and the measured magnetic field.

For example, as a result of studies of the influence of the magnetic and electric field on the twice degenerate states of the complex, it 14NV-13S shown that degeneration is removed only by a magnetic field. For the system under consideration, a transverse electric field of up to 150 kV/cm has practically no effect on the split relationship. Splitting linearly depends on the magnetic field in the range 0-0.5 Gs. Thus, preserving the degeneration of energy levels in the electric field can increase the sensitivity of magnetometry.

Earlier, NRNU MEPhI received a grant Ministry of Education and Science Russia for a project to develop multi-cube spin quantum networks based on impurity centers in diamond.