随机变数赝自旋集团展开法用于自旋玻璃研究

A CLUSTER APPROXIMATION WITH PSEUDO-SPINS OF STOCHASTIC VARIABLES TO THE RESEARCH OF SPIN GLASSES

Mano 于1977年提出一种随机变数赝自旋集团展开法,在研究稀释磁系统的铁磁性方面获得较好结果,该方法可以逐级近似,较好地计入晶格结构的影响,对互作用的性质及力程也无限制,本工作是用两种方法推广 Mano 的方法,使之可用于具有短程序参量的自旋玻璃研究。

In this paper the author proposed two methods to reform Mano's clus- ter approximation with pseudo-spins of stochastic variables,which can be used to describe spin glasses.With these methods,the random magnetic sites model and the mixed bonds model of spin glasses are solved.The first method gives what is similar with the results of mean-field method.The second one(method of double pseudo-spins of stochastic variables)gives diagrams different from the first.In proper parameters,the diagrams accord with the experiments of insulate spin glasses.Specific heat is proportional to 1/T^2 as kT/J_1>>1.The author discussed mainly the one-site approxima- tion,and also indicated the possibility of improving the results with multi- sites approximations.