STATIC VACANCIES IN A ONE-DIMENSIONAL HEISENBERG-MODEL

The effect of static vacancies created in a one-dimensional quantum an tiferromagnet has been studied. The impurity Hamiltonian is solved whe re one obtains a bound state giving rise to delta-function density of states. The longitudinal part of the impurity-host spin interaction ma kes this peak into an asymmetric algebraic singularity. It is argued t hat the bound state corresponds to a local moment in the system giving rise to Curie-like contribution to the susceptibility. The implicatio ns of the present model in the recently discovered one-dimensional ant iferromagnets such as Sr2CuO3 and Ca2CuO3 are discussed. (C) 1998 Else vier Science Ltd. All rights reserved.