SKYRMION IN A REAL MAGNETIC-FILM

Skyrmions are magnetic defects in ultrathin magnetic films, similar to the bubble domains in the thicker films. Even weak uniaxial anisotrop y determines their radii unambiguously. We derive equations of slow dy namics for Skyrmions. We show that the discreteness of the lattice in an isotropic two-dimensional magnet leads to a slow rotation of the lo cal magnetization in the Skyrmion and even a small dissipation leads t o decay of the Skyrmion. The radius of such a Skyrmion as a function o f time is calculated. We prove that uniaxial anisotropy stabilizes the Skyrmion and study the relaxation process. [S0163-1829(98)50438-9].