Soliton Approach to Spin-Peierls Antiferromagnets: Large-Scale Numerical Results

A simple intuitive picture of spin-Peierls antiferromagnets arises from regarding the elementary excitations as S=1/2 solitons. In a strictly one-dimensional system these excitations are assumed not to form bound-states and to be repelled by impurities. Couplings to the three-dimensional lattice are assumed to produce an effective confining potential which binds solitons to antisolitons and to impurities, with the number of bound-states increasing as the interchain coupling goes to 0. We investigate these various assumptions numerically in a phononless model where spontaneous dimerization arises from frustration and the interchain coupling is treated in mean field theory.