Study of Critical Phenomena in Low-Dimensional Magnets

1. S=1个连接的腐蚀链和实验结果的分析S =1个反磁链具有能量差距。但这是值得期待的，因为替代的债券链可能会在替代的某些力量上变得没有缺口。我们发现Ni（333-tet）（mu-N_3）（ClO_4）是一条带有债券替代的链条。我们做了蒙特卡罗计算和精确的诊断计算，并与Hagiwara's组的实验结果进行了比较。巧合是很好的。对自旋系统与长距离交互的长距离交互特性的研究与那些与短距离交互的系统有很大的不同。一般来说，短距离相互作用的自旋系统在一两个维度上没有相位过渡。我们研究了系统的相关长度和相位转换的低温度行为，使用几种近似值进行长距离交互。铁磁-海森堡链M的通用磁缩放函数 ... More 磁性海森伯格模型的agnetization curve of ferromagnetic Heisenberg模型在低温度方法中对某些通用扩展函数无管制地对系统是经典的或量子的事实。M=M<@D20phiM @>D2（<@D7P <@D2z @>D2H（/）T<@D12 @>D1@>D7， <@D7P <@D2z @>D2（/）LT@>D7）。Here rho<@D2s @>D2 is the硬度constant， H is magnetic field， T is the temperature， L is the length of the system， M<@D20 @>D2 is the saturation magnetization。We got phi<@D2M @>D2 （g，0） = <@D72（/）3@>D7g - <@D744（/）135@>D7g<@D13 @>D1 + <@D7752（/）2835@>D7g<@D15 @>D1 - <@D7465704（/）1913625@>D7g<@D17 @>D1 + <@D7356656（/）15591 @>D7g<@D19 @>D1 -<@D7707126486624（/）301697334375 @>D7g<@D111 @>D1 + <@D71126858624（/）4736221875@>D7g<@D113 @>D1 - <@D75083735857217648（/）20771875 @>D7g<@> D115@>D1 + ·4. Anderson transiton in random magnetic fieldWe analyzed the critical exponents of Anderson transition in random magnetic field using the transfer matrix method。我们已被认证为安德森在一年级过渡的普遍性。Less（低）

1. Critical phenomena of S=1 bond-altenating chain and analysis of experimental resultsS=1 antiferromagnetic chain has the energy gap. But it was expected that the alternating bond chain may become gapless at some strength of the alternation. We find that Ni(333-tet)(mu-N_3)(ClO_4)is such a chain with bond alternation. We did the Monte Carlo calculation and the exact diagonalization calculation and compared with experimental results by Hagiwara's group. The coincidence is very good.2. Study of spin systems with long range interactionProperties of the system with long-range interaction are quite different from those of systems with short-range interaction. Generally the short-range interacting spin systems have not phase transition in one and two dimensions. We investigated the low-temperature behavior of correlation length and phase transition of the system with long-range interaction using several approximations.3. Universal magnetic scaling function of ferromagnetic Heisenberg chainM … More agnetization curve of ferromagnetic Heisenberg model at low temperature approaches to some universal scaling function regardless to the fact that the system is classical or quantum. M=M<@D20phiM@>D2(<@D7P<@D2z@>D2H(/)T<@D12@>D1@>D7, <@D7P<@D2z@>D2(/)LT@>D7). Here rho<@D2s@>D2 is the stiffness constant, H is magnetic field, T is the temperature, L is the length of the system, M<@D20@>D2 is the saturation magnetization. We got phi<@D2M@>D2 (g, 0) = <@D72(/)3@>D7g - <@D744(/)135@>D7g<@D13@>D1 + <@D7752(/)2835@>D7g<@D15@>D1 - <@D7465704(/)1913625@>D7g<@D17@>D1 + <@D7356656(/)1515591@>D7g<@D19@>D1 - <@D7707126486624(/)3016973334375@>D7g<@D111@>D1 + <@D71126858624(/)4736221875@>D7g<@D113@>D1 - <@D75083735857217648(/)20771861407171875@>D7g<@D115@>D1 + ・・4. Numerical analysis of Anderson transiton in random magnetic fieldWe analyzed the critical exponents of Anderson transition in random magnetic field using the transfer matrix method. We certified the universality of the Anderson transition in the unitary class. Less