RANDOM ANTIFERROMAGNETIC QUANTUM SPIN CHAINS
RANDOM ANTIFERROMAGNETIC QUANTUM SPIN CHAINS
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DOI：
10.1103/physrevb.50.3799
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发表时间：
1994-08-01
影响因子：
3.7
通讯作者：
FISHER, DS
中科院分区：
文献类型：
--
作者：
FISHER, DS
本文推广了Dasgupta和Ma提出的渐近精确抽取重整化群变换，研究了具有各种随机交换耦合的自旋1/2反铁磁链的性质.随机单态相的出现，其中每个自旋与另一个可能非常远的自旋配对;也会出现更奇异的相。典型的和平均相关函数的行为进行了分析，发现是非常不同的，非常小的自旋集在长距离以及低温热力学主导后者。一些反铁磁有序相和随机单态或其他反铁磁相之间发生的相变也进行了分析。例如，如果一个小的单轴各向异性扰动被添加到一个随机海森堡反铁磁链，过渡发生从一个随机单重相到伊辛反铁磁相，因为各向异性改变sip从易平面到易轴。交错磁化在临界指数β = 8/（1+平方根7）的转变处消失。在更高的维度随机量子磁系统的性质的可能影响进行了简要的讨论。
The properties of spin-1/2 antiferromagnetic chains with various types of random exchange coupling are studied via an asymptotically exact decimation renormalization-group transformation, which is a generalization of that introduced by Dasgupta and Ma. Random-singlet phases occur in which each spin is paired with one other spin that may be very far away; more exotic phases also occur. The behavior of typical and mean correlation functions is analyzed and found to be very different, with very small sets of spins dominating the latter at long distances as well as the low-temperature thermodynamics. Some of the phase transitions that occur between antiferromapetically ordered phases and random singlet or other antiferromagnetic phases are also analyzed. For example, if a small uniaxial anisotropy perturbation is added to a random Heisenberg antiferromagnetic chain, a transition occurs from a random-singlet phase to an Ising antiferromagnetic phase, as the anisotropy changes sip from easy plane to easy axis. The staggered magnetization vanishes at the transition with critical exponent beta = 8/(1 + square-root 7). Possible implications for the properties of random quantum magnetic systems in higher dimensions are briefly discussed.