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arXiv 0904.3699cond-mat.dis-nn
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三维海森堡自旋玻璃手征和自旋有序的Monte Carlo研究

Monte Carlo studies of the chiral and spin orderings of the three-dimensional Heisenberg spin glass

Dao Xuan Viet, Hikaru Kawamura

摘要:

用广泛的蒙特卡罗模拟研究了具有最近邻无规高斯耦合的三维各向同性海森堡自旋玻璃的有序性。测量了自旋和手征的几个独立的物理量,包括相关长度比、Binder比、玻璃序参量、重叠分布函数和非自平均参数。通过控制定标修正的影响,我们得到了在非零温度下连续发生手征玻璃和自旋玻璃转变的数值证据,T_{CG} > T_{SG} > 0。因此,自旋和手征在模型的排序中是解耦的。手征玻璃指数为ν_{CG}=1.4 ± 0.2,η_{CG}=0.6 ± 0.2,表明手征玻璃转变属于不同于伊辛自旋玻璃的普适类。排除了自旋和手征扇区同时经历Kosterlitz-无旋型转变的可能性。手征玻璃态是非自平均的,可能伴随着一个类似单步的特殊复本对称性破缺。实验自旋玻璃化转变的手征性方案的影响进行了讨论。

英文摘要:

The nature of the ordering of the three-dimensional isotropic Heisenberg spin glass with nearest-neighbor random Gaussian coupling is studied by extensive Monte Carlo simulations. Several independent physical quantities are measured both for the spin and for the chirality, including the correlation-length ratio, the Binder ratio, the glass order parameter, the overlap distribution function and the non-self-averageness parameter. By controlling the effect of the correction-to-scaling, we have obtained a numerical evidence for the occurrence of successive chiral-glass and spin-glass transitions at nonzero temperatures, T_{CG} > T_{SG} > 0. Hence, the spin and the chirality are decoupled in the ordering of the model. The chiral-glass exponents are estimated to be ν_{CG}=1.4+-0.2 and η_{CG}=0.6+-0.2, indicating that the chiral-glass transition lies in a universality class different from that of the Ising spin glass. The possibility that the spin and chiral sectors undergo a simultaneous Kosterlitz-Thouless-type transition is ruled out. The chiral-glass state turns out to be non-self-averaging, possibly accompanying a one-step-like peculiar replica-symmetry breaking. Implications to the chirality scenario of experimental spin-glass transitions are discussed.

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