"Exploratory Materials and Properties of 3d Transition Metal Oxides with Mott Transitions"

“具有莫特转变的 3d 过渡金属氧化物的探索性材料和性能”

• 批准号: 07237103
• 负责人: TOKURA Yoshinori
• 金额: $ 100.29万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-07237103/
• 关键词: Mott transition; perovskite; colossal magnetoresistance; 3d trandition metal oxide; metal-insulator transition; charge ordering; spin ladder; orbital orderin; 絶縁体-金属転移; キャリヤード-ピング

The aim of this project was to perform systematic and comprehensive study on the Mott transition as well as on the anomalous metallic state near it for 3d electron transition metal oxides and chalogenides.As a prototype of the filling-control Mott transition, the perovskite-type Ti-oxides have been investigated by measurements of electronic specific heat, optical spectra, photoemission spectra, and NMR to reveal the quantum critical features near the Mott transition, in particular on strongly mass-renormalized metallic states.The perovskite-type Mn-oxides, that are attracting great current interest in the light of colossal magnetoresitance (CMR) effect, are viewed as another prototype of the Mott transition system. In this project, the interrelation among the spin, charge, and orbital (lattice) dynamics has been extensively investigated by various experimental means. In particular, the presence of the anomalous metallic state relevant to the orbital dynamics has for the first time been pointed out in the present study.The charge ordering or concomitant charge/orbital ordering is one of generic features for the correlated electron. The phenomena have been investigated for the Mn-oxides and Ni-oxides by measurements of neutron scattering, transport , and optical properties as well as by unrestricted Hartree-Fock calculations to clarify the interrelation among the spin, charge, and orbital sectors.Many spin-gap systems possibly relevant to Mott transition and superconductivity have been innovated in this project and extensively investigated by magentic (NMR and neutron scattering) measurements.

本项目的目的是对3d电子过渡金属氧化物和卤化物的Mott相变及其附近的反常金属态进行系统而全面的研究，以钙钛矿型钛氧化物作为填充-控制Mott相变的原型，通过电子比热、光学光谱、光电子能谱、和核磁共振研究了Mott跃迁附近的量子临界特征，特别是在强质量重整化金属态上，钙钛矿型锰氧化物被认为是Mott跃迁系统的另一个原型。在这个项目中，自旋，电荷和轨道（晶格）动力学之间的相互关系已经通过各种实验手段进行了广泛的研究。特别是首次指出了与轨道动力学有关的反常金属态的存在，电荷有序或伴随电荷/轨道有序是关联电子的普遍特征之一，并通过中子散射、输运、和光学性质，并通过无限制的Hartree-Fock计算来阐明自旋，电荷，许多可能与Mott转变和超导性有关的自旋能隙系统在这个项目中被创新，并被Magentic公司广泛研究。（NMR和中子散射）测量。

项目成果

K.Kumagai: "NMR study of carrier dopping effects on spin gaps in spin ladder Sr14-xAxCu24O41(A=Ca,Y and La)"Phys.Rev.Lett.. 78. 1992-1995 (1997)

K.Kumagai：“核磁共振研究载流子掺杂对自旋梯 Sr14-xAxCu24O41(A=Ca,Y 和 La) 中自旋间隙的影响”Phys.Rev.Lett.. 78. 1992-1995 (1997)

J.Q.Li: "Strnctural properties and charge ordering transition in LaSr_2Mn_2O_7" MRS'97 Proceedings"Science and Technology of Magnetic Oxides". (in press). (1998)

J.Q.Li：“LaSr_2Mn_2O_7 中的结构特性和电荷有序转变”MRS97 论文集“磁性氧化物科学与技术”。

D.S.Dessau: "κ-dependent electronic sturucture,a pseudogap,and strong coupling effects in a layered magnetoresistive oxide" MRS'97 Proceedings"Science and Technology of Magnetic Oxides". (in press). (1998)

D.S.Dessau：“层状磁阻氧化物中的 κ 相关电子结构、赝能隙和强耦合效应”MRS97 论文集“磁性氧化物科学与技术”（出版中）。

Y.Okimoto: "Photonic phase control of magnetic oxides" J.Lig.Cryst.Mol.Cryst.(in press). (1998)

Y.Okimoto：“磁性氧化物的光子相位控制”J.Lig.Cryst.Mol.Cryst.（正在印刷中）。

Y.Okimoto: "Charge ordering and disordering transitions in Pr_<1-x>Ca_xMnO_3" Phys.Rev.B. 57(in press). (1998)

Y.Okimoto：“Pr_<1-x>Ca_xMnO_3 中的电荷有序和无序转变”Phys.Rev.B。