Ultra-slow spin waves propagation based on skyrmion breathing

Spin wave has attracted significant attention in various fields because of its rich physics and potential applications in the development of spintronics devices in the post-Moore era. However, the analog of a subluminal-like propagation in the field of spin waves has not been well discussed. Here, we theoretically demonstrate the ultra-slow spin waves propagation in a nanoscale two-dimensional ferromagnetic film in the presence of magnon-skyrmion interaction. The minimum spin waves propagation velocity was estimated to be as low as 1.8 m s-1 by adjusting the system parameters properly, and the spin waves group delay and advance are dynamically tunable via the intensity or detuning of the control field, which allows the possibility of observing superluminal- and subluminal-like spin waves propagation in a single experimental setup. These results deepen our understanding of the spin wave-skyrmion interactions, open a novel and efficient pathway to realize ultra-slow spin waves propagation, and are expected to be applied to magnetic information storage and quantum operations of magnons.