The generation and propagation of magnetic excitations such as magnons and spin waves in ferromagnetic thin films provides a platform for the development of spin-based device technology. Koerner et al. report measurements on the magnetization dynamics of a nickel–iron film excited coherently by microwave magnetic fields from a coplanar wave guide. Using nitrogen vacancy center–based magnetometry and a time-resolved magneto-optical Kerr effect, the authors show that low excitation frequencies and low bias fields in the range of only a few milli-tesla results in the generation of magnons emitted at higher frequency. Extending over 60 harmonics of the excitation frequency, such upconversion of magnetic excitation frequencies should prove useful for spintronics applications.

C. Koerner, R. Dreyer, M. Wagener, N. Liebing, H. G. Bauer, and G. Woltersdorf: Frequency multiplication by collective nanoscale spin-wave dynamics - Science 375, 1165 (2022) - DOI: 10.1126/science.abm6044