Magnetic susceptibility due to disorder-induced neutral solitons in interacting polymer chains.
(1999) Magnetic susceptibility due to disorder-induced neutral solitons in interacting polymer chains. Physical Review B 59(21), 13882-13891.
We study the magnetic response due to neutral solitons induced by disorder in polymer materials. We account for interchain interactions, which, if sufficiently strong, result in a bond-ordered phase, in which the neutralsolitons are bound into pairs. We analytically calculate the corresponding pair size distribution. As the spins of the solitons have a distance dependent antiferromagnetic coupling, this allows us to calculate the magnetic susceptibility in the ordered phase. At low temperatures, the result deviates from the usual Curie behavior in a way that depends on the relative strength of the disorder and the interchain interactions. We compare our results to the observed magnetic susceptibility of trans-polyacetylene and we suggest new experiments extending towards lower temperatures.