Dynamical Properties of two-leg spin ladders and bond-alternating spin chaions

双腿自旋梯和键交替自旋链的动力学性质

基本信息

批准号：
14540336
负责人：
SUGA Sei-ichiro
金额：
$ 1.41万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540336/
关键词：
S=1 bond-alternating spin chain dynamical structure factor transverse magnetic fields Tomonaga-Luttinger liquid NMR relaxation rate incommensurate magnetic order optical absorption spectra Kondo insulator 垂直磁揚ハルデーンギャップ数値厳密対角化動的平均場

项目摘要

(1) Dynamical properties of S=1 bond-alternating spin chains in transverse fieldsS=1 bond-alternating spin chains exhibit a quantum phase transition between the Haldane-gap phase and the dieter phase depending on the bond-alternating ratio. Recent inelastic neutron-scattering experiments revealed that typical compounds in respective phases NDMAP and NTENP show different dynamical properties in transverse magnetic fields. We have calculated dynamical structure factors of NDMAP and NTENP in transverse magnetic fields. From the analysis of field dependence of the one-magnon isolated model and the excitation continuum, we have shown that the characteristic field dependence results in the different field dependence of the excitation continuum.(2) Field-induced incommensurate state in frustrated S=1/2 bond-alternating spin chains in magnetic fieldsIn a typical S=1/2 bond alternating spin-chain compound F_5PNN, non-trivial temperature dependence of the NMR relaxation rate was observed in magn … More etic fields. We have investigated critical properties of the system in magnetic fields by introducing the next-nearest-neighbor interaction, and explained the experimental findings in viewpoint of the Tomonaga-Luttinger liquid. Furthermore, taking account of the interchain interaction by mean field theory, we have shown that the incommensurate ordered state takes place around the half-value of the magnetization saturation.(3) Optical absorption spectra in S=1/2 spin laddersOptical absorption spectra in S=1/2 two-leg spin ladders are investigated by the RVB description and the numerical diagonalization method. We have shown that the shoulder structure caused by the cyclic four spin interaction appears in addition to the ordinary two-mignon peak. On the basis of the numerical results, the frequencies for the shoulder and peak of a typical compound SrCu_2O_3 are evaluated.(4) Field induced phase transition in Kondo insulatorOn the basis of the periodic Anderson model, we have obtained the temperature field phase diagram of the Kondo insulator, combining dynamical-mean-field theory and quantum Monte Carlo technique. As field is increased in low temperatures, the phase transition among Kondo insulator-antiferromagnet-spin polarized metal occurs. Slightly above the antiferromagnetic transition temperature, heavy-fermion states with the enhanced mass are realized. Its origin was discussed in viewpoint of the one particle spectrum and the dynamical spin susceptibility. Less

（1）横向场中S = 1个键抗自旋链的动力学特性= 1键偏置旋转链暴露于Haldane-差距相位和Dieter相之间的量子相变，具体取决于键偏置的比例。最近的无弹性中子散射实验表明，相对相的NDMAP和NTENP中的典型化合物在横向磁场中显示出不同的动态特性。我们计算了横向磁场中NDMAP和NTENP的动态结构因子。 From the analysis of field dependence of the one-magnon isolated model and the excitement continuum, we have shown that the characteristic field dependence results in the different field dependence of the excitement continuum.(2) Field-induced incommensurate state in frustrated S=1/2 bond-alternating spin chains in magnetic fieldsIn a typical S=1/2 bond alternative spin-chain compound F_5PNN, non-trivial temperature dependence在Magn…更多的ETEC场中观察到NMR弛豫率。我们已经通过引入下一个最邻近的相互作用来研究系统在磁场中的临界特性，并在tomonaga-luttinger液体的角度解释了实验发现。此外，考虑到平均场理论的链相互作用，我们已经表明，磁化饱和度的半价值发生在磁化饱和度的半价值周围。（3）S = 1/2 Spin Spin Spin spin spin梯级惊喜光谱S = 1/2 = 1/2两腿spin ladders rvb的描述和数字化的方法进行了数字化方法。我们已经表明，除了普通的两米峰外，还出现了由环状四旋相互作用引起的肩部结构。根据数值结果，评估了典型化合物SRCU_2O_3的肩和峰值的频率。（4）（4）我们在周期性安德森模型的基础中磁场诱导的相位过渡，我们已经获得了近niSulator的温度场相图，结合了动态 - 毫米型理论，结合了动态 - 毫米型杂音和量子量。随着低温下场的增加，发生了近托绝缘子 - 抗抗铁旋转旋转极化金属之间的相变。略高于抗铁磁过渡温度，重力质量具有增强的质量。在一个粒子频谱和动态旋转易感性的角度讨论了其起源。较少的