Low-energy excitations of spin-Peierls chains with modified bond-impurities
arXiv:cond-mat/9908134 · doi:10.1103/PhysRevB.61.6741
Abstract
The introduction of modified bond-defects in spin-Peierls systems is investigated in a model of antiferromagnetic Heisenberg spin chains coupled to adiabatic phonons. Generically, new low-energy magnetic or non-magnetic excitations appear below the bulk spin gap energy. When two adjacent bonds are modified, these excitations can be interpreted in terms of boundstates of a soliton with the localized spin-1/2 located on the impurity site. It is shown that the confining potential occurs even in the case of {\it isolated} chains.
final version, to appear in Phys. Rev. B