Probing GHz gravitational waves with graviton–magnon resonance Asuka Ito, Tomonori Ikeda, Kentaro Miuchi and Jiro Soda Eur. Phys. J. C, 80 3 (2020) 179 Published online: 27 February 2020 DOI: 10.1140/epjc/s10052-020-7735-y