Spin flop in one-dimensional quantum antiferromagnets

The field-induced transition corresponding to the spin flop in the quantum antiferromagnetic chains in the presence of the Ising-like single-ion anisotropy D (<0) is studied by the finite-cluster analysis. It is found that for $S\geq {3\over 2}$ a first-order metamagnetic transition occurs even in one dimension for small negative D except for the Haldane phase, while there exist two second-order transitions and an incommensurate phase appears between them for intermediate D, as already found for S=1. We also discuss on some experiments of CsNiCl$_3$ related with the present work.