Magnetization plateaux of the S = 5/2 antiferromagnetic chain with anisotropies

The magnetization process of the S=5/2 antiferromagnetic chain with coupling and single-ion anisotropies is investigated using numerical diagonalization of finite-size clusters and level spectroscopy analysis. Various magnetization plateaux are found at 1/5, 2/5, 3/5, and 4/5 of the saturation magnetization. Plateaux without translational symmetry breaking are predicted to occur at 1/5 and 3/5 magnetization. A symmetry-protected topological plateau phase is found at 3/5 magnetization, but not at 1/5. In addition translational-symmetry-broken plateaux induced by large coupling anisotropy are found at 1/5, 2/5, 3/5, and 4/5 magnetization. Phase diagrams at 1/5, 2/5, 3/5, and 4/5 of the saturation magnetization are obtained. Magnetization curves for several representative anisotropies are also presented, together with the corresponding magnetic phase diagrams.