Tunable space-time crystal in room-temperature magnetodielectrics
Alexander J. E. Kreil, Halyna Yu. Musiienko-Shmarova, Sebastian Eggert, Alexander A. Serga, B. Hillebrands, Dmytro A. Bozhko, Anna Pomyalov, Victor S. L’vov · Physical review. B./Physical review. B · 2019
We report the experimental realization of a space-time crystal with tunable periodicity in time and space in a magnon Bose-Einstein condensate (BEC), formed in a room-temperature yttrium iron garnet (YIG) film by a microwave space-homogeneous magnetic field. The magnon BEC is prepared to have a well-defined frequency and nonzero wave vector. We demonstrate how the crystalline ``density'' as well as the time and space textures of the resulting crystal may be tuned by varying the experimental parameters: External static magnetic field, temperature, thickness of the YIG film, and power of the microwave field. The proposed space-time crystals provide an additional dimension for exploring dynamical phases of matter and can serve as a model nonlinear Floquet system, that brings in touch the rich fields of classical nonlinear waves, magnonics, and periodically driven systems.