Nonlinear surface spin waves on ferromagnetic media with inhomogeneous exchange anisotropies: soliton solutions

Yan Xu ^a,∗, Gang Su ^{b ,} De-sheng Xue ^a , Huai-zhong Xing ^a , Fa-shen Li ^a

a Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, China b Department of Physics, Graduate School, Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039, China

Received 2 November 2000; accepted 1 December 2000 Communicated by V.M. Agranovich

Abstract The nonlinear surface spin waves in ferromagnets with pure inhomogeneous exchange anisotropies have been considered. The boundary condition for magnetization of this system is derived. The nonlinear dispersion relation for these waves is obtained, and the modulation of the inhomogeneous exchange constants is investigated. The two-dimensional nonlinear Schrödinger equation satisfied by the spin-wave envelope amplitude is derived for the first time, and conditions for the existence of a single solitonic solution are discussed. A soliton solution is presented as an example.  2001 Elsevier Science B.V. All rights reserved. PACS: 75.30.Ds; 75.30.Pd