9502781 Wysin This U.S.-Brazil Collaborative Research grant will support the research of Gary Wysin, Kansas State University, in collaboration with A. S. T. Piers and M. E. Gouvea of the Universidade Federal de Minas Gerais to perform theoretical and computational analyses of the properties of topological nonlinear excitations in quasi-two-dimensional magnets. The research will extend the current understanding of the properties of the vortex, soliton, and spinwave excitations in these systems. The magnetic properties of topological excitations will be determined partly by perturbation theory from exactly known solutions, and partly by numerical simulations. The proposed studies will provide a better understanding of the particular spin structures that make up the topological excitations in two-dimensional magnets, as well as determine the internal normal modes of the excitations. An important contribution will be the characterization of the role of topological excitations in the phase transitions in such magnets. While topological defects have been shown to be significant factors in phase transitions in superfluids and superconductors, in liquid crystals, and in other physical systems, the proposed work will carry the investigation of these effects to easy-plane and easy-axis two-dimensional magnets. The Brazilian group brings experience in the analytical study of such properties, while the U.S. group has experience in computer simulation of the same class of properties. ***
