Calabrese Pasquale, Pelissetto Andrea, Vicari Ettore
Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 2, Pisa, Italy.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Feb;77(2 Pt 1):021126. doi: 10.1103/PhysRevE.77.021126. Epub 2008 Feb 27.
We consider the three-dimensional randomly diluted Ising model and study the critical behavior of the static and dynamic spin-spin correlation functions (static and dynamic structure factors) at the paramagnetic-ferromagnetic transition in the high-temperature phase. We consider a purely relaxational dynamics without conservation laws, the so-called model A. We present Monte Carlo simulations and perturbative field-theoretical calculations. While the critical behavior of the static structure factor is quite similar to that occurring in pure Ising systems, the dynamic structure factor shows a substantially different critical behavior. In particular, the dynamic correlation function shows a large-time decay rate which is momentum independent. This effect is not related to the presence of the Griffiths tail, which is expected to be irrelevant in the critical limit, but rather to the breaking of translational invariance, which occurs for any sample and which, at the critical point, is not recovered even after the disorder average.
我们考虑三维随机稀释伊辛模型，并研究高温相中顺磁 - 铁磁转变处静态和动态自旋 - 自旋关联函数（静态和动态结构因子）的临界行为。我们考虑一种无守恒律的纯弛豫动力学，即所谓的模型A。我们给出了蒙特卡罗模拟和微扰场论计算结果。虽然静态结构因子的临界行为与纯伊辛系统中的非常相似，但动态结构因子显示出显著不同的临界行为。特别是，动态关联函数显示出与动量无关的长时间衰减率。这种效应与格里菲斯尾的存在无关，预计在临界极限中它是无关紧要的，而是与平移不变性的破坏有关，这种破坏发生在任何样本中，并且在临界点，即使经过无序平均也不会恢复。
