arXiv:cond-mat/9809038 · Physical review. B, Condensed matter
Response of finite spin- S Heisenberg chains to local perturbations
Örs Legeza, Jenő Sólyom
Abstract
We consider the properties of finite isotropic antiferromagnetic Heisenberg chains with $S=1/2,1,3/2$ spins when a weak magnetic field is applied on a few sites, using White's density-matrix renormalization-group method. For the $S=1$ chain there exists only one length scale in the system which determines the behavior of the one- and two-point correlation functions both around the local perturbation and near the free boundary. For the critical half-odd-integer spin cases the exponent of the spin-spin correlation function was found to be $\ensuremath{\eta}=1$ and the exponent of the decay of the site magnetization around the perturbed site is ${x}_{m}=\ensuremath{\eta}/2.$ Close to a free boundary, however, the behavior is completely different for $S=1/2$ and $S>1/2.$