Solid-state spin defects, particularly the nitrogen-vacancy (NV) centers in diamond, are promising for applications such as single-photon sources, sensing, and imaging at the nanometer scale. Indeed, their excellent spin properties enable sensing magnetic fields, electric fields, temperatures, and strain. Single NV center offers the opportunity for sensing with sub-10 nm spatial resolution. However, using an ensemble of NV centers is essential to achieve higher sensitivity. But, the process of creating a diamond with high NV density results in lots of undesirable defects in the diamond. Some of these defects are a source of magnetic noise, and some are electron traps that destabilize the NV centers' charge states.
In this talk, I will discuss the complex interplay of spin- and charge-related processes in an ensemble of NV centers in diamond in the high NV density regime. I will show how charge state dynamics can get in the way of spin-based sensing and experimental protocols to mitigate them.