Theoretical research on orbital orders and fluctuations

轨道序数和涨落的理论研究

• 批准号: 11220204
• 负责人: KURAMOTO Yoshio
• 金额: $ 19.39万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas (B)
• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11220204/
• 关键词: ORBITAL DEGENERACY; f ELECTRONS; d ELECTRONS; SUPERCONDUCTIVITY; FERROMAGNETISM; ORBITAL ORDER; QUADRUPOLE MOMENT; OCTUPOLE MOMENT; 反強磁性; バンド理論; 近藤効果; 多極子秩序

Theoretical study was made on the following aspects.*Microscopic study of interactions for orbital orderWe explained the origin of characteristic wave numbers in the ordering pattern of rare-earth hexaborides.*Band theory taking account of the orbital orderWe developed a new calculational scheme within the so-called LDA+U method in order to derive the band structure in the presence of orbital orders. The results clarify the relashionship between the band structure and the physical properties.*Theory of orbital degrees of freedom and magnetic order(1) CeB6 : In the quadrupole ordered phase of CeB6, we have predicted that magnetic field induces staggered octupoles. Within this project natural explanation for the phenomena was provided on the basis of analyzing interaction among Ce ions. Furthermore, we pointed out the importance of pseudo-dipolar interactions in understanding the orthogonal arrangement of nearest-neighbor moments in CeB6.(2) Yb4As3 : Charge ordering of this compound leads to a characteristic magnetic property at low temperature. We derived the effective Hamiltonian for the system, which describes accurately the anisotropy including the Dzyaloshinski-Moriya interaction.(3) TmTe : This compound has the cubic symmetry and has the crystalline-electric-field ground state. Hence we examined the character of the quadrupole order and magnetic moment induced by magnetic field, in comparsion with CeB6.

理论研究是在以下方面进行的。*轨道订购的相互作用的微观研究在稀有地点六边形的订购模式中解释了特征波数的起源。结果阐明了带结构与物理特性之间的重新占领。*轨道自由度和磁性秩序的理论（1）CEB6：在CEB6的四极有序阶段，我们已经预测了磁场会引起交错的八杆。在该项目中，根据分析CE离子之间的相互作用提供了对现象的自然解释。此外，我们指出了伪 - 二色相互作用在CEB6中最近邻邻矩的正交布置中的重要性。（2）YB4AS3：该化合物的电荷排序在低温下导致特征性的磁性。我们为该系统提供了有效的哈密顿量，该系统准确地描述了包括dzyaloshinski-Moriya相互作用的各向异性。（3）TMTE：该化合物具有立方对称性，并具有结晶电场的基态。因此，我们检查了与CEB6相抵触的磁场引起的四极阶和磁矩的特征。

项目成果

R.Shiina,H.Shiba and O.Sakai: "Theory of Antiferro-Quadrupolar Ordering in a Weak-Crystal-Field System TmTe"Physica B. 284&288. 1335-1336 (2000)

R.Shiina、H.Shiba 和 O.Sakai：“弱晶体场系统 TmTe 中的反铁四极有序理论”Physica B.284

J.Akimitsu, ...(2 authors) H.Harima, Y.Kuramoto: "High-Temperature Ferromagnetism in CaB_2C_2"Science. 293. 1125-1127 (2001)

J.Akimitsu，...（2 位作者）H.Harima，Y.Kuramoto：“CaB_2C_2 中的高温铁磁性”科学。

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)。

H.Kusunose, Y.Kuramoto: "Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions"J. Phys. Soc. Jpn.. 70. 1751-1761 (2001)

H.Kusunose，Y.Kuramoto：“轨道简并性和多极相互作用导致的非共线磁性”J。

H.Shiba,O.Sakai,R.Shiina: "Nature of Ce-Ce interaction in CeB_6 and its consequences"J.Phys.Soc.Jpn. 68. 1988 (1999)

H.Shiba,O.Sakai,R.Shiina：“CeB_6 中 Ce-Ce 相互作用的性质及其后果”J.Phys.Soc.Jpn。