Numerical Study on the Ground-State Phase Diagram of the S = 1/2 XXZ Ladder Model

Takeshi Narushima, Satoshi Takada, Tola Nakamura

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19 Citations (Scopus)


The ground-state phase diagram of the S = 1/2 XXZ ladder model is investigated by using the density-matrix renormalization-group method. This model is composed of two S = 1/2 XXZ chains with ferromagnetic rung couplings (λ) and intra-chain anisotropy (Δ), and continuously changes from the two independent S = 1/2 XXZ chains at λ = 0 to the S = 1 XXZ chain in the limit of λ → ∞. It is shown that there exist edge states at Δ = 1 and λ = 1 in relation to the four-fold degeneracy of the ground state and that an excitation gap opens nearly at λ = 0 for 0.8 ⩽Δ ⩽ 1. In addition, it is clarified that the transition between the Haldane phase and the antiferromagnetic phase occurs at λ= 1.15 ± 0.01 for Δ = 1. A possible phase diagram in the λ-Δ plane is proposed, which is consistent with the scaling analysis based on the bosonization method.

Original languageEnglish
Pages (from-to)4322-4330
Number of pages9
Journaljournal of the physical society of japan
Issue number11
Publication statusPublished - 1995
Externally publishedYes


  • Haldane state
  • S = 1/2 XXZ ladder model
  • density-matrix renormalization-group method

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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