NV centers in diamond are prototypical quantum sensors and have demonstrated their remarkable sensing capabilities over the past decade. This work describes the application of single NV centers as nanoscale magnetic field sensors under cryogenic conditions. Their sensing properties are studied in dependence of temperature and regimes of enhanced sensitivity are identified. The setup of a variable temperature scanning NV-probe microscope is presented and characterized, enabling high-resolution mapping of magnetic fields. Finally, investigations of a chiral lattice magnet demonstrate a spatial resolution of 20 nm and pave the way for quantitative studies of static and dynamic local magnetism at low temperatures.
