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.

本文从以下几个方面进行了理论研究。轨道有序相互作用的微观研究我们解释了稀土六硼化物有序模式中特征波数的来源。考虑轨道阶的能带理论我们在LDA+U方法中发展了一种新的计算方案，以便在存在轨道阶的情况下导出能带结构。结果阐明了能带结构和物理性质之间的关系。轨道自由度和磁序理论（1）CeB 6：在CeB 6的四极有序相中，我们预言磁场诱导出交错的八极。本课题在分析Ce离子间相互作用的基础上，对这一现象给出了自然解释。此外，我们指出了伪偶极相互作用在理解CeB 6中最近邻矩的正交排列中的重要性。(2)Yb 4As 3：这种化合物的电荷有序导致低温下的特征磁性。我们导出了系统的有效哈密顿量，它精确地描述了包括Dzyaloshinski-Moriya相互作用的各向异性。(3)TmTe：该化合物具有立方对称性，具有晶体电场基态。因此，我们研究了四极级和磁场诱导的磁矩的性质，与CeB 6相比。

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

H.Shiba,O.Sakai and R.Shiina: "Nature of Ce-Ce interaction in CeB_6 and its consequences"J.Phys.Soc.Jpn.. 68. 1988-1993 (1999)

H.Shiba、O.Sakai 和 R.Shiina：“CeB_6 中 Ce-Ce 相互作用的性质及其后果”J.Phys.Soc.Jpn.. 68. 1988-1993 (1999)

H.Harima: "LDA+U Method Applied for f-electron Systems"J.Magn. Magn. Mater.. 226-230. 83-84 (2001)

H.Harima：“LDA U 方法应用于 f 电子系统”J.Magn。

H.Harima: "FLAPW Electronic Band Structure of Skutterudite and Filled Skutterudite Cpmpounds"Progress of Theoretical physics Supplement. 138. 117-118 (2000)

H.Harima：“方钴矿和填充方钴矿化合物的FLAPW电子能带结构”理论物理进展补充。

N.Fukushima,T.Kuromaru,H.Kusunose and Y.Kuramoto: "Theory of magneto-elastic properties of interacting multipoles"Physica B : Condensed Matter. 281-282. 538-539 (2000)

N.Fukushima、T.Kuromaru、H.Kusunose 和 Y.Kuramoto：“相互作用多极子的磁弹性特性理论”物理学 B：凝聚态物质。