Level statistics of XXZ spin chains with a random magnetic field
Level statistics of XXZ spin chains with a random magnetic field
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DOI：
10.1103/physrevb.69.132404
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发表时间：
2003-10
影响因子：
3.7
通讯作者：
K. Kudo;T. Deguchi
中科院分区：
文献类型：
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作者：
K. Kudo;T. Deguchi
数值研究了随机磁场下自旋XXZ链的能级间距分布。我们明确地表明如何水平统计依赖于晶格尺寸L，各向异性参数A，和随机磁场h的平均振幅。在能谱中，量子可积性与来自随机性的不可积性竞争，其中XXZ相互作用被参数A修改。当Δ≠0时，能级间距分布主要表现为Wigner行为，而当Δ=0时，尽管系统由于随机性而不可积，但仍表现为Poisson行为。在大h极限下，Δ φ 0也出现类似泊松的行为。此外，能级间距分布取决于晶格尺寸L，特别是当无规场较弱时。
The level-spacing distribution of a spin- 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 A, 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 A. 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.