ONE-DIMENSIONAL HEISENBERG-ANTIFERROMAGNET OF ARBITRARY SPIN IN A STRONG MAGNETIC-FIELD

The behavior of a one-dimensional isotropic Heisenberg antiferromagnet of arbitrary spin in a strong magnetic field is studied in terms of an equivalent Bose-gas problem. The cases of spin 1/2 and classical spins are described by different limits of the ''Bose gas with repulsion'' model. The square-root dependence of magnetization on field is obtained in both cases, but in the quantum case one should use a properly defined effective-interaction constant, while in the classical case the result may be obtained with a ''bare'' interaction. We find in addition that the region of linear behavior of the magnetization for classical spins is also covered partially by the Bose-gas approximation.