摘要翻译：
在自旋交叉材料中，分子的体积随其处于高自旋(HS)或低自旋(LS)状态而变化。这种变化引起晶格的畸变。这些畸变之间的弹性相互作用对自旋跃迁现象的协同性质起着重要作用。我们发现这种弹性相互作用引起的临界行为属于平均场普适性范畴，其中自发磁化强度和磁化率的临界指数分别为$\beta=1/2$和$\gamma=1$。此外，自旋-自旋关联函数在长距离时是常数，与短程模型相比，它不表现出指数衰减。在远距离下，相关函数的值表现出不同的大小依赖关系:$O(1/N)$，$O(1/\sqrt{N}）$，在临界温度以上、临界温度下和临界温度以下的常数分别为$O(1/N)$，$O(1/\sqrt{N}）。该模型不显示簇，甚至在临界点附近也不显示簇。我们还发现，在该模型中，团簇生长受到抑制，在共存区不存在临界乳光。在磁滞回线末端亚稳态的弛豫过程中，没有观察到形核现象，在HS和LS分数的变化过程中保持了空间均匀的构型。平均场模型的这些特性不仅在自旋交叉材料中被发现，而且在弹性畸变介导局域态相互作用的系统中也被发现。
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英文标题：
《Realization of the mean-field universality class in spin-crossover
  materials》
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作者：
Seiji Miyashita, Yusuk\'e Konishi, Masamichi Nishino, Hiroko Tokoro,
  Per Arne Rikvold
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Materials Science        材料科学
分类描述：Techniques, synthesis, characterization, structure.  Structural phase transitions, mechanical properties, phonons. Defects, adsorbates, interfaces
技术，合成，表征，结构。结构相变，力学性质，声子。缺陷，吸附质，界面
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一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  In spin-crossover materials, the volume of a molecule changes depending on whether it is in the high-spin (HS) or low-spin (LS) state. This change causes distortion of the lattice. Elastic interactions among these distortions play an important role for the cooperative properties of spin-transition phenomena. We find that the critical behavior caused by this elastic interaction belongs to the mean-field universality class, in which the critical exponents for the spontaneous magnetization and the susceptibility are $\beta = 1/2$ and $\gamma = 1$, respectively. Furthermore, the spin-spin correlation function is a constant at long distances, and it does not show an exponential decay in contrast to short-range models. The value of the correlation function at long distances shows different size-dependences: $O(1/N)$, $O(1/\sqrt{N})$, and constant for temperatures above, at, and below the critical temperature, respectively. The model does not exhibit clusters, even near the critical point. We also found that cluster growth is suppressed in the present model and that there is no critical opalescence in the coexistence region. During the relaxation process from a metastable state at the end of a hysteresis loop, nucleation phenomena are not observed, and spatially uniform configurations are maintained during the change of the fraction of HS and LS. These characteristics of the mean-field model are expected to be found not only in spin-crossover materials, but also generally in systems where elastic distortion mediates the interaction among local states.
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PDF链接：
https://arxiv.org/pdf/710.0921