Annihilation dynamics of magnetic skyrmion lattice state under in-plane magnetic field and spontaneous recovery after field removal

Nanoscale magnetic skyrmions are potential candidates for information carriers, for which the nonvolatility under external stimuli is critical to the stability of recorded bits. Here, we present a micromagnetic study on the annihilation dynamics of a two-dimensional skyrmion lattice under a transverse magnetic field and the recoverability of the topological charge after removing the field. The temporal and spatial correlation functions and their Fourier transforms of the spin system reveal position-dependent dynamics under the transverse field. The slow modes ( 10 GHz) hosted by all spins determine the spin configurations, and the fast ones ( 10 GHz) around the skyrmion core region control the dynamics of topological properties. A dynamic critical time tcri, when the field-induced ferromagnetic nuclei begin to be long-range correlated, is proved by statistical analyses of their spatial distribution over time. If turning off the transverse field before tcri, the collective motion of the spin system can restore the previously lost topological charge. Our results guide the realization of nonvolatile information storage in skyrmion lattice, thus widening the possibility of skyrmion-based devices for future spintronics-based nanocomputing.