H. Yue et Nn. Huang, SOLITON-SOLUTIONS FOR A SPIN CHAIN WITH AN EASY-PLANE AND THE METHOD OF RIEMANN PROBLEM WITH ZEROS, Journal of physics. A, mathematical and general, 30(1), 1997, pp. 331-344
With the procedure to solve explicitly the equations of the Riemann ma
trix with poles, multi-soliton solutions to the Landau-Lifshitz (L-L)
equation for a spin chain with an easy plane are found formally, and a
single soliton solution is given explicitly.