Physic and Chemistry of Oxygen Holes : Phase Transitions and Dynamics in High-Valence Transition-Metal Oxides

氧空穴的物理和化学:高价过渡金属氧化物的相变和动力学

• 批准号: 12304018
• 负责人: FUJIMORI Atsushi
• 金额: $ 30.28万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12304018/
• 关键词: Fe oxides; charge disproportionation; single crystal thin films; single crystal growth; Moessbauer spectroscopy; high pressure; photoemission spectroscopy; orbital ordring; ホール効果

・ We have succeeded in synthesizing single crystalline thin films of perovskite-type oxides SrFeO_3, CaFeO_3 and SrFe_<0.5>Co_<0.5>O_3 containing unusually high valence Fe^<4+> and Co^<4+> ions. The films were fabricated using the laser ablation technique and subsequent oxidation using ozone. We discovered unusual anomalous Hall effect in SrFeO_3 thin film・ Charge disproportionation in perovsfcite-lype Fe oxides were studied using photoemission spectroscopy and Hartree-Fock band-structure calculations. It was found that electron-lattice interaction plays an important role in the charge disproportionation in CaFeO_3 whereas the charge disproportionation occurs purely electronically in La_<1/3>Sr_<2/3>FeO_<3->.・ Moessbauer measurements of CaFeO_3 Sr_<2/3>La_<1/3>FeO_<3-> were made under high pressure in order to study the pressure dependence of charge disproportionation and magnetic ordering. We found that under high pressure, Sr_<2/3>La_<1/3>FeO_<3-> becomes a ferromagnet with a high Cu … More rie temperature.・ We performed Moessbauer measurements on a double-layer perovskite Sr_3Fe_2O_7, and a triple-layer perovskite LaSr_3Fe_3O_<10> and discovered charge disproportionatian in these compounds. We also found helical magnetic ordering in Sr_3Fe_2O_7, and a collinear one in LaSr_3Fe_3O_<10->.・ Inelastic nuclear resonant scattering of synchrotron radiation was made on CaFeO_3 and Sr_<2/3>La_<1/3>FeO_<3-> Changes in the Fe local phonon density of states were observed across the charge ordering temperature.・ In the measurements of the nuclear resonance scattering from CaFeO_3 and Sr_<2/3>La_<1/3>FeO_3, a dramatic change in the intensity of the elastic peak across the magnetic phase transition was discovered.・ Element-selective inelastic nuclear resonance scattering measurements from ^<161>Dy and ^<57>Fe nuclei were made on perovskite-type DyFeO_<3->. The local phonon density of states of Dy and Fe thus obtained were compared with shell-model calculations, and the mode assignment was made.・ By the measurements of magnetic circular dichroism in soft-x-ray absorption, the electronic and magnetic states of SrFe_<1-x>Co_xO_3 and their changes induced by Co substitution were identified.・ Single crystals of PrNiO_3 were synthesized under high pressure. It was found that across the metal-insulator transition, the symmetry is lowered from orthorhombic to monoclinic. Furthermore, charge disproportionation at the Ni sites were confirmed in the insulating monoclinic phase.・ Triclinic perovskite PrNi0_3 was synthesized under high pressure. The Bi atoms at the Asites were found to charge-disproportinate into Bi^<3+> and Bi^<5+>. We found that, when La^<3+> ions were substituted for the Bi ions, a metal-insulator transition occurred as a function of atomic composition.・ On the basis of photoemission results on perovskite-type Ni oxides, we proposed that there are two kinds of metallic states within the well-known metallic phase, namely, the conventional Pauli-paramagnetic phase and the Curie-Weiss paramagnetic phase with a peudogap. Less

·我们成功地合成了钙钛矿型氧化物SrFeO_3、CaFeO_3和SrFe_ Co_ O_3的单晶薄膜<0.5><0.5>，其中含有异常高价的Fe^&lt;4+&gt;和Co^&lt;4+&gt;离子。该膜是使用激光烧蚀技术和随后的氧化使用臭氧。在SrFeO_3薄膜中发现了异常的霍尔效应。用光电子能谱和Hartree-Fock能带计算研究了钙钛矿型铁氧化物中的电荷分离。结果表明，CaFeO_3中的电荷分离是电子-晶格相互作用的结果，而La_（1/3）Sr_（2/3）FeO_3中的电荷分离是纯电子作用的结果<3->。在高压下对CaFeO_3Sr_（2/3）La_（1/3）FeO_3进行了穆斯堡尔谱测量<3->，以研究电荷极化和磁有序的压力依赖性。我们发现在高压下，Sr_（2/3）La_（1/3）FeO_（2/3）<3->成为铁磁体，Cu含量较高 ...更多信息 rie温度。我们对双层钙钛矿结构的Sr_3Fe_2O_7和三层钙钛矿结构的LaSr_3Fe_3O_7进行了穆斯堡尔谱测量，<10>发现它们都存在电荷双折射现象。在Sr_3Fe_2O_7和LaSr_3Fe_3O_7中分别发现了螺旋磁有序和共线磁有序<10->。用同步辐射的非弹性共振散射方法在CaFeO_3和Sr_（&lt;2/3&gt;La_（1/3））FeO_3上进行了研究，<3->观察到Fe局域声子态密度随电荷有序温度的变化。在CaFeO_3和Sr_（2/3）La_（1/3）FeO_3的核磁共振散射测量中，发现在磁相变过程中弹性峰的强度发生了剧烈的变化。本文<161><57>报道了钙钛矿型DyFeO_2的~（13）Dy和~（13）Fe原子核的选择性非弹性核共振散射测量<3->。将由此得到的Dy和Fe的局域声子态密度与壳模型计算结果进行了比较，并进行了模式分配。通过软X射线吸收的磁圆二色性测量，确定了SrFe_ Co_xO_3的电子态和磁态<1-x>以及Co取代引起的电子态和磁态的变化。在高压下合成了PrNiO_3单晶。研究发现，在金属-绝缘体转变过程中，对称性从斜方晶系降低到单斜晶系。此外，在绝缘单斜相中，证实了Ni位的电荷分离。在高压下合成了三斜晶系钙钛矿PrNi0_3。发现Bi原子在A位上发生电荷不成比例地转变为Bi^&lt;3+&gt;和Bi^&lt;5+&gt;。我们发现，当La^&lt;3+&gt;离子取代Bi离子时，发生了金属-绝缘体转变，这是原子组成的函数。基于对钙钛矿型Ni氧化物的光电子能谱研究结果，我们提出了在已知的金属相中存在两种金属态，即常规的Pauli顺磁相和具有赝隙的Curie-Weiss顺磁相。少

项目成果

M.I.Larkin: "Exponential Field Distribution in Sr(Cu_<1-x>Zn_x)_2O_3"Physica B. 289-290. 153-156 (2000)

M.I.Larkin：“Sr(Cu_<1-x>Zn_x)_2O_3 中的指数场分布”Physica B. 289-290。

J.Mesot: "Determination of the Fermi Surface in High-T_c Superconductors by Angle-Resolved Photoemission Spectroscopy"Phys. Rev. B. 63. 224516-1-224516-4 (2001)

J.Mesot：“通过角分辨光电发射光谱测定高温超导体中的费米面”Phys。

A.Masuno: "Transport and Magnetic Properties of the Micro-Fabricated Perovskite-Type Manganese Oxides"Physica C. (印刷中).

A. Masuno：“微加工钙钛矿型锰氧化物的输运和磁性”Physica C.（出版中）。

T.Saitoh: "Strontium-doped Lanthanum Manganese Oxides Studied by XPS"Surface Science Spectra. 6. 292-301 (1999)

T.Saitoh：“通过 XPS 研究的掺锶镧锰氧化物”表面科学光谱。

M. Azuma: "New S=1/2 Akemating Chain Compound - High Pressure Form of (VO)_2P_2O_1 -"Acta Physica Polonica A. 97. 205-208 (2000)

M. Azuma：“新的 S=1/2 Akemating 链化合物 - (VO)_2P_2O_1 的高压形式 -”Acta Physica Polonica A. 97. 205-208 (2000)