Magnetization plateau of the S = 1 spin ladder with anisotropies

The magnetization process of the S = 1 spin ladder with two anisotropies competing each other is investigated using the numerical diagonaization of finite-size clusters and the level spectroscopy analysis. As a result, it is found that the translational symmetry broken magnetization plateaux appear at 1/4 and 3/4 of the saturation magnetization. The phase diagrams with respect to the anisotropies at the 1/4, 1/2 and 3/4 magnetizations are obtained. The magnetization curves for several typical parameters are also presented.