Partially Disorered Dipole-and Staggered Quadrupole-Ordering in Spin Systems with Competing Interactions

具有竞争相互作用的自旋系统中的部分紊乱偶极子和交错四极子排序

基本信息

批准号：
14540359
负责人：
IDOGAKI Toshihiro
金额：
$ 1.79万
依托单位：
Kyushu 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 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540359/
关键词：
Competing Spin System Dipole Quadrupole Partially Disorered Phase Staggered Ordering

项目摘要

In the present study, we performed through and systematic investigations of the stability and the physical origin of characteristic types of dipole and/or quadrupole orderings in the systems with frustration inducing bilinear and/or biquadratic exchange interactions.Main results are as follows ;1)For bilinear-biquadratic exchange ± J Ising model, we performed the non-equilibrium relaxation MC calculation and clarified that randomness weakens the re-enntrant phenomena of ferromagnetic dipole ordering but not affects on the ataggered quadrupole ordering. The critical exponents depend (not depend) on the randomeness for the dipole (quadrupole) ordering.2)In order to discuss the partially disordered states in the axial next nearest neighbor Ising (ANNNI) model, we proposed two extended models, i.e. (i) intralayer exchang alternating model and (ii) mixed spin model. By using standard MC and site dependent molecular field calculation, for both models we confirmed the stability of partially disordered states and the importance of entropy contribution for occurence of the partially disordered states.3)We have investigated the effects of the biquadratic interactions on 3D classical plane rotator model with stacked triangular lattice geometry by use of histogram MC simulation methods. We obtained complete magnetic phase diagrams for the system, and clarified the nature of appearing various pahases including incommensurate-or chiral dipole (quadrupole) ordering, etc.

In the present study, we performed through and systematic investigations of the stability and the physical origin of characteristic types of dipole and/or quadrupole orderings in the systems with frustration induced bilinear and/or biquadratic exchange interactions.Main results are as follows ;1)For bilinear-biquadratic exchange ± J Ising model, we performed the non-equilibrium relaxation MC calculation and clarified that randomness weakens the铁磁偶极子订购的重新植物现象，但不会影响四极杆的订购。关键示例取决于（不取决于）偶极子（四极杆）排序的随机性。2）为了讨论轴向下一个最近的邻居（Annni）模型中部分无序状态，我们提出了两个扩展模型，即（i）Intralayer Exchange替代模型和（II）混合旋转模型。通过使用标准的MC和依赖于现场的分子场计算，对于这两个模型，我们确认了部分无序状态的稳定性以及熵贡献对发生部分无序状态的发生的重要性。3）我们已经研究了Biquadratic相互作用对3D经典旋转器模型与堆叠的三角形晶状体模型的3D经典旋转器模型的影响，该效果是通过图像模拟方法模拟的。我们获得了该系统的完整磁相图，并阐明了出现各种Pahase的性质，包括不一致或手性偶极子（四倍）排序，等等。