Magnetization plateau in S=3/2 antiferromagnetic Heisenberg chain with anisotropy

The magnetization process of the S=3/2 antiferromagnetic Heisenberg chain with the single-ion anisotropy D at T=0 is investigated by the exact diagonalization of finite clusters and finite-size scaling analyses. It is found that a magnetization plateau appears at m=1/2 for $D>D_c=0.93 \pm 0.01$. The phase transition with respect to D at D_c is revealed to be the Kosterlitz-Thouless-type. The magnetization curve of the infinite system is also presented for some values of D.