Chirality mechanism of spin-glass ordering

自旋玻璃作为挫折和随机性共存的“复杂”系统的典型例子已经被广泛研究。本项目的目的是测试最近提出的实验自旋玻璃有序的手征性机制的有效性，以解释实验中的一些难题。通过对各向同性和弱各向异性的三维海森堡自旋玻璃模型在零场中的大规模模拟，我们证实了在有限温度下没有标准自旋玻璃序的手性玻璃转变的发生。在真实的自旋玻璃中，弱而有限的随机磁各向异性不可避免地存在，并有望在自旋玻璃有序化中发挥重要作用。我们还进行了大规模的模拟弱各向异性系统，并得到了支持的结果发生的旋手性重新耦合预测的手征机制。我们还对磁场中的三维海森堡自旋玻璃进行了大规模模拟，发现在磁场中也发生了与零场相同的手征玻璃转变，在零场极限下，相关的转变线的形状是规则的。同样，结果与手性机制的预测一致。

Spin glass has been studied quite extensively as a typical example of 'complex' systems where the effects of frustration and randomness coexist. The present project has been performed with the aim of testing the validity of the chirality mechanism of the experimental spin-glass ordering proposed recently to explain some of the puzzles of the experiments. Via large-scale simulations on isotropic as well as weakly anisotropic three-dimensional Heisenberg spin-glass models in zero field, we have confirmed the occurrence of the chiral-glass transition at a finite temperature without the standard spin-glass order. In real spin glasses, weak but finite random magnetic anisotropy inevitably exits and is expected to play an important role in the spin-glass ordering. We have also performed large-scale simulations on the weakly anisotropic systems and have obtained the results supporting the occurrence of the spin-chirality recoupling predicted by the chirality mechanism. We have also performed large-scale simulations for the three-dimensional Heisenberg spin glass in magnetic fields, and found that the chiral-glass transition of the same kind as in zero field occurs, the shape of the associated transition line being regular in the zero-field limit. Again, the results are consistent with the prediction of the chirality mechanism.