Magnetization plateaux in the antiferromagnetic Ising chain with single-ion anisotropy

Two one-dimensional spin-1 anti ferromagnetic Ising models with a single-ion anisotropy under external magnetic field at low temperatures are exactly investigated by the transfer-matrix technique. The magnetization per spin (in) is obtained for the two types of models (denoted by model 1 and 2) as an explicit function of the magnetic field (H) and of the anisotropy parameter (D). Model 1 is an extension of the one recently treated by Ohanyan and Ananikian [V.R. Chanyan, N.S. Ananikian, Phys. Lett. A 307 (2003) 761: we have generalized their model to the spin-1 case and a single-ion anisotropy term have been included. In the limit of positive (or null) anisotropy (D >= 0) and strong antiferromagnetic coupling (alpha = J(A)/J(F) >= 3) the m x H curves are qualitatively the same as for the spin S = 1/2 case, with the presence of only one plateau at m/m(sal) = 1/3. On the other hand, for negative anisotropy (D < 0) we observe more plateaux (m = 1/6 and 2/3), which depend on the values of D and a. The second model (model 2) is the same as the one recently studied by Chen et al. [X.Y. Chen, Q. Jiang, W.Z Shen, C.G. Zhang, J. Mag. Mag. Mat. 262 (2003) 2581 using Monte Carlo simulation; here, the model is treated within an exact transfer-matrix framework. (C) 2008 Elsevier Ltd. All rights reserved.