Nonlinear dynamics for magnetic systems with a single-spin potential with variable shapes J.-P. Nguenang, A. Kenfack-Jiotsa and T. C. Kofané Eur. Phys. J. B, 48 4 (2005) 519-528 Published online: 19 January 2006 DOI: 10.1140/epjb/e2006-00001-9