Coupled charge and spin dynamics in high-density ensembles of nitrogen-vacancy centers in diamond

Abstract

We studied the spin depolarization of ensembles of nitrogen-vacancy (NV) centers in nitrogenrich single crystal diamonds. We found a strong dependence of the evolution of the polarized state in the dark on the concentration of NV centers. At low excitation power, we observed a simple exponential decay profile in the low-density regime and a paradoxical inverted exponential profile in the high-density regime. At higher excitation power, we observed complex behavior, with an initial sharp rise in luminescence signal after the preparation pulse followed by a slower exponential decay. Magnetic field and excitation laser power-dependent measurements suggest that the rapid initial increase of the luminescence signal is related to recharging of the nitrogen-vacancy centers (from neutral to negatively charged) in the dark. The slow relaxing component corresponds to the longitudinal spin relaxation of the NV ensemble. The shape of the decay profile reflects the interplay between two mechanisms: the NV charge state conversion in the dark and the longitudinal spin relaxation. These mechanisms, in turn, are influenced by ionization, recharging and polarization dynamics during excitation. Interestingly, we found that charge dynamics are dominant in NV-dense samples even at very feeble excitation power. These observations may be important for the use of ensembles of NV centers in precession magnetometry and sensing applications. arXiv:1801.00047v1 [cond-mat.mes-hall]

Selective measurement of charge dynamics in an ensemble of nitrogen-vacancy centers in nanodiamond and bulk diamond

“…It was demonstrated that an ensemble of NV centers could be stable enough to be used as a charge based data storage medium [23,24]. Other studies on dense ensembles of NVs and near-surface single NVs reported a strong interplay between charge and spin dynamics during illumination as well as in the dark that can interfere with spin measurements [13,25,26]. Disentangling the two contributions is critical to understand the underlying physical mechanisms, and to enable effective control of charge dynamics in many applications.…”

Dynamic Quantum Sensing of Paramagnetic Species Using Nitrogen-Vacancy Centers in Diamond

“…Whilst recombination may not factor in this work, ionization of the NVcharge state may be an important factor particularly owing to the CW illumination used. Indeed, ionization of NVis known to be a function of optical illumination time 54 and illumination intensity 55 .…”

Magnon condensation in a dense nitrogen-vacancy spin ensemble

“…This is considered bearing in mind that the long-range structural and electronic perturbations that could occur for concentrations approaching this value may further decrease this limit, especially when considering the presence of neighbouring non-N-V − defects, such as 14/15 N and 13 C atoms. For example, in light of the N-V − systems unique charge-state dynamics [33], a finite concentration of electron donors, such as the 14/15 N defect, is necessary to ensure that the N-V − → N-V 0 conversion rate is negligible. Therefore, their relative density may also encourage the formation of aggregates and further limit the electronic integrity-retaining concentration.…”

“…Exceptionally, there are reports of concentrations exceeding 10 ppm and approaching 100 ppm [31][32][33]. This encourages the consideration of higher concentrations, and the optimistic outlook that there are no intrinsic limitations, as growth optimisation techniques and N-V − creation efficiencies are continuously improved.…”