NV-center relaxometry of magnetic insulating systems

NV-centers have been recently growing into popularity due to their minimally invasive and high resolution magnetic field sensing. In this work, we specifically focus on NV-centers relaxometry as a method of probing of collective excitations in magnetic insulators. We develop a general framework that connects the experimentally-measurable relaxation times of the probe to the properties of the magnetic system in terms of the transverse and longitudinal noise emitted by the later. Providing a first rigorous definition for the chemical potential of an antiferromagnetic system, we discuss how it can be extracted via a noise local measurement. Moreover, our results show that NV-relaxometry can be effectively deployed to image low-lying collective excitations such as antiferromagnetic solitons, as well as they open up new prospects in probing transport properties and regimes of spin waves in the absence of interfacial effects.