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arXiv 0802.0089cond-mat.stat-mechcond-mat.dis-nn
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三维随机场伊辛模型的热临界行为和普适性

Thermal critical behavior and universality aspects of the three-dimensional random-field Ising model

A. Malakis, N. G. Fytas

摘要:

利用N重Wang-Landau算法研究了三维双峰随机场伊辛模型。本征能量子空间由最近发展的临界最小能量子空间技术确定,并利用该方案的两个实现。随机场是从双峰离散$(\pmΔ)$分布,我们研究了模型的各种值的无序强度$Δ$,$Δ=0.5, 1, 1.5$和2,立方晶格与线性尺寸$L=4-24$。我们提取信息的概率分布的特定的热峰的样本的随机场。这使我们能够得到相图并给出比热的有限尺寸行为。饱和比热的问题被重新检查,它表明,开放的问题的普遍性的随机场伊辛模型的强烈影响,缺乏自平均的模型。这种性质似乎是实质上取决于无序强度。

英文摘要:

The three-dimensional bimodal random-field Ising model is investigated using the N-fold version of the Wang-Landau algorithm. The essential energy subspaces are determined by the recently developed critical minimum energy subspace technique, and two implementations of this scheme are utilized. The random fields are obtained from a bimodal discrete $(\pmΔ)$ distribution, and we study the model for various values of the disorder strength $Δ$, $Δ=0.5, 1, 1.5$ and 2, on cubic lattices with linear sizes $L=4-24$. We extract information for the probability distributions of the specific heat peaks over samples of random fields. This permits us to obtain the phase diagram and present the finite-size behavior of the specific heat. The question of saturation of the specific heat is re-examined and it is shown that the open problem of universality for the random-field Ising model is strongly influenced by the lack of self-averaging of the model. This property appears to be substantially depended on the disorder strength.

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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