title: Effects of a space modulation on the behavior of a 1D alternating Heisenberg spin-1/2 model.
abstract: The effects of a magnetic field (h) and a space modulation (δ) on the magnetic properties of a one-dimensional antiferromagnetic-ferromagnetic Heisenberg spin-1/2 model have been studied by means of numerical exact diagonalization of finite size systems, the nonlinear σ model, and a bosonization approach. The space modulation is considered on the antiferromagnetic couplings. At δ = 0, the model is mapped to a gapless Lüttinger liquid phase by increasing the magnetic field. However, the space modulation induces a new gap in the spectrum of the system and the system experiences different quantum phases which are separated by four critical fields. By opening the new gap, a magnetization plateau appears at ½M(sat). The effects of the space modulation are reflected in the emergence of a plateau in other physical functions such as the F-dimer and the bond-dimer order parameters, and the pair-wise entanglement.
authors: Department of Physics, University of Guilan, Rasht, Iran. Mahdavifar@guilan.ac.ir
authors: Saeed
authors: S
authors: Mahdavifar
authors: Jahanfar
authors: J
authors: Abouie