Collapse of a skyrmion due to the discreteness of a crystal lattice in isotropic two-dimensional ferro- and antiferromagnets has been studied analytically and by numerical solution of equations of motion for up to 2000 x 2000 classical spins on a square lattice coupled via Heisenberg exchange interaction. Excellent agreement between analytical and numerical results has been achieved. The lifetime of the skyrmion scales with its initial size, lambda_0, as(lambda_0/a)^5 in ferromagnets and as (lambda_0/a)^2.15 in antiferromagnets, with a being the lattice parameter. This makes antiferromagnetic skyrmions significantly shorter lived than ferromagnetic skyrmions.
Cai, L., Chudnovsky, E. M., & Garanin, D. A. (2012). Collapse of skyrmions in two-dimensional ferromagnets and antiferromagnets. Physical Review B - Condensed Matter and Materials Physics, 86(2) DOI: 10.1103/PhysRevB.86.024429