Nonlinear Magnetic Sensing with Hybrid Nitrogen-Vacancy/Magnon Systems.

Magnetic sensing beyond the linear regime could broaden the frequency range of detectable magnetic fields, which is crucial to various microwave and quantum applications. Recently, nonlinear interactions in diamond nitrogen-vacancy (NV) centers are proposed to realize magnetic sensing across arbitrary frequencies. In this work, we enhanced these capabilities by exploiting the nonlinear spin dynamics in hybrid systems of NV centers and ferri- or ferromagnetic (FM) thin films. We studied the frequency mixing effect in the hybrid systems and demonstrated that the introduction of FM films not only amplifies the intensity of nonlinear resonance signals that are intrinsic to NV spins but also enables novel frequency mixing through parametric pumping and nonlinear magnon scattering effects. The discovery and understanding of the magnetic nonlinearities in hybrid NV/magnon systems position them as a prime candidate for magnetic sensing with a broad frequency range and high tunability, particularly meaningful for nanoscale, dynamical, and noninvasive materials characterization.