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 investigated by various numerical techniques. We show that, generically, a Heisenberg spin chain coupled to dynamical optical phonons exhibits a transition 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.