Theoretical Studies of Low Dimensional Quantum Magnets with Spatial Structures

具有空间结构的低维量子磁体的理论研究

基本信息

批准号：
11640366
负责人：
HIDA Kazuo
金额：
$ 1.6万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

1. One-dimensional random quantum magnetsUsing the density matrix renormalization group (DMRG) method, we have shown that the Haldane state in spin-1 1-dimensional Heisenterg antiferromagnet is stable against randomness.2. One-dimensional quasiperiodic quantum magnetsUsing DMRG, the ground state of spin-1/2 1-dimensional quasipenodic antiferromagnetic XXZ model is investigated. It is shown that the Fibonacci modulation, which is critical in the XY model, becomes relevant in the presence of the antiferromagnetic Ising interaction and the low energy behavior is modified drastically.The one-dimensional half-filled Fibonacci Hubbard model is investigated using DMRG and perturbational renormalization group method. It is shown that a varity of ground states are realized even in the half-filled case. Experimental observation of these phases is expected using the quantum dot array and other systems. Our results suggest the importance of the strong correlation effect in quasiperiodic systems.3. … More One-dimensional quantum magnets with long spatial periodicityUsing the exact diagonalization method, the ground state and magnetization process of various one-dimensional quantum magnets with long spatial periodicity are investigated and universality class and critical exponents of quantum phase transition are clarified.4. Kagome lattice quantum antiferromagnetGround state and low energy exciatation spectrum of the spin-1 kagomee antiferromagnet which is realized in an organic material are investigated by the exact diagonalization and cluster expansion method. It is shown that both magnetic and non-magnetic excitations have finite energy gaps. The hexagonal singlet solid picture is proposed in which the frustration is fully compensated by quantum fluctuation. It is also shown that a magnetization plateau appears at 1/3 of full magnetization.Future projectsThe project with the same subject is approved and the following investigations are in progress.(1) Magnetization process of random one-dimensional quantum magnets(2) Finite temperature properties of the kagome antiferromagnets(3) Ground state phase diagram of S=1 1-dimensional XXZ model with single-site anisotropy(4) Studies of magnetization plateaux in quasi-1-dimensional and quasi-2-dinensional quantum magnets using the bond operator method Less

1。一维随机量子磁磁磁性磁置矩阵重新归一化组（DMRG）方法，我们已经表明，Spin-1 1二维Heisenterg抗fiferromagnet中的Haldane态稳定。2。研究了一维准二元量子磁磁磁铁DMRG，Spin-1/2 1维准苯甲酸抗铁磁性XXZ XXZ模型的基态。结果表明，在XY模型中至关重要的斐波那契调制在存在抗磁性ISING相互作用和低能量行为的情况下变得很重要。使用DMRG和扰动重新归一化组方法研究了一维半填充的斐波那契哈伯德模型。结果表明，即使在半填充的情况下，地面状态也会实现。使用量子点阵列和其他系统，可以预期对这些相的实验观察。我们的结果表明，在准膜系统中，强相关效应的重要性3。 …研究了更多具有长空间周期性的一维量子磁铁，通过精确的对角度方法，研究了具有长空间周期性的各种一维量子磁体的基态和磁化过程，并阐明了量子相变的普遍性类别和量子的关键指数。4。 Kagome晶格量子抗铁磁场状态和在有机材料中实现的Spin-1 kagomee抗fiferromagnet的低能量探针谱，通过精确的对角度化和簇扩展方法研究了。结果表明，磁性激发和非磁性激发具有有限的能量差距。提出了六边形的单线固体图片，其中挫败感通过量子波动充分补偿。 It is also shown that a magnetization plateau appears at 1/3 of full magnetization.Future projectsThe project with the same subject is approved and the following investigations are in progress.(1) Magnetization process of random one-dimensional quantum magnets(2) Finite temperature properties of the kagome antiferromagnets(3) Ground state phase diagram of S=1 1-dimensional XXZ model with single-site anisotropy(4) Studies of使用键操作员方法较少