On-site magnetization in open antiferromagnetic chains: A classical analysis versus NMR experiments in a spin-1 compound - art. no. 012409

The response of an open spin chain with isotropic antiferromagnetic interac tions to a uniform magnetic field is studied by classical Monte Carlo simul ations. It is observed how the induced on-site magnetization is nonuniform, due to the occurrence of edge staggered terms which decay exponentially ov er a distance equal to the zero-field correlation length of the infinite ch ain. The total magnetic moment associated to each staggered termis found to be about half of the original single-spin magnitude and to decrease as the inverse of temperature (i.e., to behave as Curie-like moment). The numeric al results are compared to recent NMR findings in spinless-doped Y2BaNiO5; the remarkable agreement found shows that, for temperatures above the Halda ne gap, the classical approach gives a correct picture of the boundary effe cts observed in the Heisenberg S = 1 chain.