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中国物理学会期刊

次近邻作用对随机量子Ising系统动力学性质的影响

CSTR: 32037.14.aps.59.1499

Effects of next-nearest-neighbor interactions on the dynamics of random quantum Ising model

CSTR: 32037.14.aps.59.1499
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  • 利用递推关系方法在高温极限下研究了具有次近邻自旋耦合相互作用的一维随机量子Ising系统的动力学性质,求解了系统的自关联函数及谱密度.假设自旋耦合参量或横向磁场满足双高斯分布,研究发现当随机变量的标准偏差σJ(σB)较小时系统的动力学性质存在从集体模行为到中心峰值行为的交跨效应,当σJ (σB)较大时,交跨效

     

    The dynamics of one-dimensional random quantum Ising model with both nearest-neighbor and next-nearest-neighbor (NNN) interactions is investigated in the high temperature limit by the method of recurrence relations. Spin autocorrelations and the corresponding spectral densities of the system are calculated. Supposing that the exchange couplings (or the transverse fields) satisfy the double-Gaussian distribution, the effects of this distribution on the dynamics of the system is studied. The results show that the dynamics of the system undergoes a crossover from a collective-mode behavior to a central-peak one when the standard deviations σJ(or σB)of the random variables are small and there is no crossover when σJ(or σB)are large. Meanwhile, the effects of NNN interactions on the dynamics of the system are studied. It is found that the central-peak behavior becomes more obvious and the collective-mode behavior becomes weaker as Ki increase, especially when Ki>Ji/2(Ji and Ki are exchange couplings of the NN and NNN interactions, respectively). However, the effects are small when the NNN interactions are weak (KiJi/2).

     

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