Strong high-frequency spin waves released periodically from a confined regionZhen-Wei Zhou, Xi-Guang Wang, Yao-Ghuang Nie, Qing-Lin Xia and Guang-Hua GuoEur. Phys. J. Appl. Phys., 91 3 (2020) 30601DOI: https://doi.org/10.1051/epjap/2020200144