Optically detected ferromagnetic resonance in diverse ferromagnets via nitrogen vacancy centers in diamond

We report measurements of optically detected ferromagnetic resonance (ODFMR) in thin films using nitrogen-vacancy (NV) centers in diamond, whose fluorescence intensity changes in response to the ferromagnetic resonance (FMR) excitation of a proximal ferromagnet. Here, we extend the study of the off-resonant and broadband detection of FMR, first observed in the magnetic insulator YIG to a diverse set of ferromagnetic materials. We measure ODFMR signals from several technologically relevant metallic ferromagnetic materials including Py, Co, Co2(Mn0.6Fe0.4)Ge, and an insulating NiZnAl ferrite. These results show the generality of the spin-relaxation based coupling of the NV spins to the ferromagnetic dynamics that enables this detection. The observable field-frequency range of the ODFMR signal is dependent on material parameters such as saturation magnetization and damping. These results imply that NV-based ODFMR can give insights into nanoscale ferromagnetic dynamics and its damping processes, especially for samples with low magnetization and in the low field-frequency regime, which is important for several technologies.