Особенности высокочастотной ЭПР/ЭСЭ/ОДМР спектроскопии NV-дефектов в алмазе

Abstract

Methods of high-frequency electron paramagnetic resonance (EPR), electron spin echo (ESE), and optically detectable magnetic resonance (ODMR) were used to study the unique properties of nitrogen-vacancy defects (nitrogen-vacancy NV center) in diamond in strong magnetic fields. It has been shown that in strong magnetic fields (3 to 5 T), an effective optically-induced alignment of populations of spin levels occurs, with filling of the MS=0 level and emptying of the MS=1 levels, which allowed to observe ODMR via variations of the photoluminescence intensity, reaching 10% at resonance. It has been demonstrated that this efficiency in high magnetic fields is of the same order as that in zero and low magnetic fields. The samples were preliminarily studied by ODMR in zero magnetic fields, which made it possible to accurately determine the main parameters of the fine structure and hyperfine interactions with nitrogen nuclei, as well as dipole-dipole interactions between the NV center and deep nitrogen donors (nitrogen atom replacing carbon, N0). In the spectra of high-frequency ODMR, hyperfine interactions with the nearest carbon atoms (13C isotope) were observed, which opens up possibilities for optical measurements of the processes of dynamic nuclear polarization of carbon in strong magnetic fields. Narrow ODMR lines in high magnetic fields are supposed to be used to measure these fields with submicron spatial resolution. A new method for detecting ODMR of NV centers with modulation of the microwave frequency has been developed, which simplifies the technique of measuring high magnetic fields. A significant increase in the intensity of the ODMR signal at orientation of the magnetic field along the symmetry axis of NV center was demonstrated.