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arXiv 0706.0628cond-mat.dis-nncond-mat.stat-mech
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三维随机场伊辛模型中相变的性质

On the nature of the phase transition in the three-dimensional random field Ising model

Victor Dotsenko

摘要:

本文简要回顾了近三十年来随机场伊辛模型的理论、数值和实验研究。本文讨论了具有高斯随机场的三维随机场中的相变性质。利用简单的标度论证,证明了当随机场随机场的强度不太小(大于某一阈值)时,该系统的有限温度相变等价于低温有序-无序相变。用简单的概率论和修正的平均场方法(考虑了最近邻自旋-自旋关联)对零温相变进行了详细的研究。结果表明,如果所有的热激活过程都被抑制,则铁磁序参量m(h)作为随机场强度$h$的函数将变得与历史有关.特别地,磁化曲线m(h)对于增大和减小$h$的行为揭示了磁滞回线。

英文摘要:

A brief survey of the theoretical, numerical and experimental studies of the random field Ising model during last three decades is given. Nature of the phase transition in the three-dimensional RFIM with Gaussian random fields is discussed. Using simple scaling arguments it is shown that if the strength of the random fields is not too small (bigger than a certain threshold value) the finite temperature phase transition in this system is equivalent to the low-temperature order-disorder transition which takes place at variations of the strength of the random fields. Detailed study of the zero-temperature phase transition in terms of simple probabilistic arguments and modified mean-field approach (which take into account nearest-neighbors spin-spin correlations) is given. It is shown that if all thermally activated processes are suppressed the ferromagnetic order parameter m(h) as the function of the strength $h$ of the random fields becomes history dependent. In particular, the behavior of the magnetization curves m(h) for increasing and for decreasing $h$ reveals the hysteresis loop.

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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