Dynamical effects of phonons on soliton binding in quasi-one-dimensional spin-Peierls systems

The role of dynamical magneto-elastic coupling in spin-Peierls chains is in vestigated by Various numerical techniques. We show that, generically, a He isenberg spin chain coupled to dynamical optical phonons exhibits a transit ion towards a spontaneously dimerized state. The low energy excitations are characterized as topological solitons. No binding between solitons occurs in the isolated spin-phonon chain. However, elastic interchain coupling can lead to the formation of bound states. (C) 1999 Elsevier Science B.V. All rights reserved.