Ordering and Dynamics of Multipolar Moments

多极矩的排序和动力学

• 批准号: 13640381
• 负责人: SHIBA Hiroyuki
• 金额: $ 0.9万
• 依托单位: Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640381/
• 关键词: charge ordering; quadrupolar order; octupolar order; multipolar moment; neutron scattering; CeB_6; Yb_4As_3; NpO_2; CeB6; Yb4As3; 八重極モーメント; 磁場誘起ギャップ; 軌道秩序; 多重極モーメ

The main results in this project are as follows.The charge ordering may be viewed as the zeroth-order multipolar ordering. From this viewpoint we studied the charge ordering of Yb4As3, in which one-dimensional chains of Yb^<3+> ions are formed. We have carefully derived a low-energy effective Hamiltonian to describe the one-dimensional chain. As a result, we have succeeded in showing the presence of Dzyloshinksy-Moriya term due to the unique structure of this material. Moreover, the nature of the excitation spectrum in the chain has been studied in detail and compared with available neutron-scattering experiments.The most important problem in this project was to study multipolar dynamics in quadrupolar order phase of CeB6. The equilibrium properties of the quadrupolar order were studied by us before. Under this project we extended our study for dynamics, which can be explored experimentally by applying the magnetic field and by using neutron scattering. In fact A. Bouvet carried out such an experiment 10 years ago in his Ph. D. thesis. Because of lack of any reliable theory at that time his experimental results have not been seriously analyzed. According to our theory field-induced staggered octupolar moments are important in CeB6. We have compared our theory with Bouvet's experiment and have achieved a good agreement.As a third topic, we studied in general materials having Γ8 crystal-field ground state. They include TmTe and NpO2. In such systems multipolar moments beyond quadrupolar ones are crucial. We have studied interactions between multipolar moments using the symmetry of the crystal structure. In addition we have examined field-induced antiferromagnetic moments in TmTe and have explained some of the features observed in experiment.

本课题的主要结果如下：电荷序可以看作是零阶多极序。从这个观点出发，我们研究了Yb^<3+>离子形成一维链状结构的Yb_4As_3的电荷有序性。我们仔细地推导了一个低能有效哈密顿量来描述一维链。因此，我们成功地证明了由于这种材料的独特结构而存在的Dzyloshinksy-Moriya项。此外，还详细研究了CeB 6链中激发谱的性质，并与中子散射实验进行了比较。本项目的主要问题是研究CeB 6四极有序相的多极动力学。我们以前研究过四极序的平衡性质。在这个项目下，我们扩展了我们的动力学研究，可以通过施加磁场和使用中子散射进行实验探索。事实上，A. Bouvet在10年前的博士学位中进行了这样的实验。论文由于当时缺乏可靠的理论，他的实验结果没有得到认真的分析。根据我们的理论，场致交错八极矩是重要的CeB 6。我们的理论与Bouvet的实验进行了比较，取得了很好的一致性。第三，我们研究了具有Γ8晶体场基态的一般材料。它们包括TmTe和NpO 2。在这样的系统中，四极矩之外的多极矩是至关重要的。利用晶体结构的对称性，我们研究了多极矩之间的相互作用。此外，我们还研究了TmTe中的场致反铁磁磁矩，并解释了实验中观察到的一些特征。

项目成果

斯波 弘行: "電子相関の物理"岩波書店. 198 (2001)

Hiroyuki Shiba：“电子关联物理学”岩波书店 198 (2001)。

Seizo Watarai: "Entropy Effect on the Magnetization Process of Hexagonal XY-like Heisenberg Antiferromagnets"Journal of Physical Society of Japan. 70, No.2. 532-537 (2001)

Seizo Watarai：“熵效应对六方XY型海森堡反铁磁体磁化过程的影响”日本物理学会杂志。

Osamu Sakai: "Invariant Form of Multipolar Interactions and Relation between Antiferro-Quadrupolar Order and Field-Induced Magnetic Moments"Journal of Physical Society of Japan. 72(No.5に出版予定). (2003)

Osamu Sakai：“多极相互作用的不变形式以及反铁四极秩序和场感应磁矩之间的关系”日本物理学会杂志72（即将出版第5期）。

Hiroyuki Shiba: "Theory of Field-Induced Gap Formation in Charge-Ordered Yb4As3"Physics B. 312-313. 309-314 (2002)

Hiroyuki Shiba：“电荷有序 Yb4As3 中场致间隙形成的理论”物理学 B. 312-313。

Hiroyuki Shiba: "Structure, Effective Hamiltonian and Magnetic Exciattion Spectrum In Charge-Ordered Yb4As3"Proceedings of French-Japanese Workshop on Quantum Properties of Low-Dimensional Antiferromagnets (Kyushu University Press). 183-190 (2002)

Hiroyuki Shiba：“电荷有序 Yb4As3 的结构、有效哈密顿量和磁激发谱”法国-日本低维反铁磁体量子特性研讨会论文集（九州大学出版社）。