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arXiv 2109.00552cond-mat.str-elcond-mat.stat-mech
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具有键无序的Haldrons链的动力学性质

Dynamical properties of the Haldane chain with bond disorder

Jing-Kai Fang, Jun-Han Huang, Han-Qing Wu, Dao-Xin Yao

摘要:

利用Lanczos精确对角化和量子MonteCarlo结合随机解析延拓方法,研究了具有不同键序强度的$S=1$反铁磁Heisenberg链的动力学性质.在弱无序区,我们发现弱耦合键,可以诱导额外的低能量激发低于一个磁振子模式。随着无序度的增加,随着越来越多的低能激发的出现,平均Half带隙在$δ_Δ\sim 0.5$处闭合。在达到临界无序强度$δ_c\sim 1$后,系统进入无规单重态相,在动态自旋结构因子$ω=0$处有明显的尖峰,在$ω>0$处有宽的连续区.此外,我们还分析了随机自旋畴的分布,并在数值上发现了三种具有有效自旋1/2量子或自旋1位的畴。这些“自旋”可以形成弱耦合的长程单线态,这是由于量子涨落导致的在$ω=0$处的尖峰。

英文摘要:

By using Lanczos exact diagonalization and quantum Monte Carlo combined with stochastic analytic continuation, we study the dynamical properties of the $S=1$ antiferromagnetic Heisenberg chain with different strengths of bond disorder. In the weak disorder region, we find weakly coupled bonds which can induce additional low-energy excitation below the one-magnon mode. As the disorder increases, the average Haldane gap closes at $δ_Δ\sim 0.5$ with more and more low-energy excitations coming out. After the critical disorder strength $δ_c\sim 1$, the system reaches a random-singlet phase with prominent sharp peak at $ω=0$ and broad continuum at $ω>0$ of the dynamic spin structure factor. In addition, we analyze the distribution of random spin domains and numerically find three kinds of domains hosting effective spin-1/2 quanta or spin-1 sites in between. These "spins" can form the weakly coupled long-range singlets due to quantum fluctuation which contribute to the sharp peak at $ω=0$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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