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Paper   IPM / P / 12026
School of Physics
  Title:   Effects of a Space Modulation on the Behavior of a 1D Alternating Heisenberg Spin-1/2 Model
1.  S. Mahdavifar
2.  J. Abouie
  Status:   Published
  Journal: J. Physics: Condens. Matter
  Vol.:  23
  Year:  2011
  Pages:   246002 (9pp)
  Supported by:  IPM
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 [1/2]Msat. 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.

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