Level statistics of XXZ spin chains with a random magnetic field

Kazue Kudo, Tetsuo Deguchi

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


The level-spacing distribution of a spin-1/2 XXZ chain is numerically studied under random magnetic field. We show explicitly how the level statistics depends on the lattice size L, the anisotropy parameter Δ, and the mean amplitude of the random magnetic field h. In the energy spectrum, quantum integrability competes with nonintegrability derived from the randomness, where the XXZ interaction is modified by the parameter Δ. When Δ ≠ 0, the level-spacing distribution mostly shows Wigner-like behavior, while when Δ = 0, Poisson-like behavior appears although the system is nonintegrable due to randomness. Poisson-like behavior also appears for Δ ≠ 0 in the large h limit. Furthermore, the level-spacing distribution depends on the lattice size L, particularly when the random field is weak.

Original languageEnglish
Article number132404
Pages (from-to)132404-1-132404-4
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number13
Publication statusPublished - 2004 Apr
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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