In the era of gravitational wave astronomy/cosmology, it is important not only to improve the sensitivity of existing detectors but also to extend detectable frequency range with novel methods. The speaker and his collaborators show that gravitational waves can induce resonant spin precessions of electrons (magnon) in the presence of an external magnetic field. This phenomenon, they call it graviton-magnon resonance, enables them to probe gravitational waves in the Gigahertz (GHz) frequency range. Furthermore, they give upper limits on GHz gravitational waves by utilizing measurements of resonance fluorescence of magnons.
