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

· We have succeeded in synthesizing single crystalline thin films of perovskite-type oxides SrFeO_3、CaFeO_3和<0.5>SrFe_Co_O_3<0.5>含有异常高的valence Fe^&lt;4+&gt; and Co^&lt;4+&gt; ions。这部电影是用激光爆炸技术和使用臭氧的亚序氧化法制造的。我们发现了SrFeO_3薄膜中不寻常的反常霍尔效应，在perovsfcite-lite Fe氧化物中使用光发射光谱学和Hartree-Fock波段结构计算进行了研究。它发现了电子晶格相互作用在CaFeO_3中的电荷分配中起着重要的作用，而电荷分配在La_&lt;1/3&gt; Sr_&lt;2/3&gt; FeO_&lt;3-&gt;。Moessbauer measurements of CaFeO_3 Sr_&lt;2/3&gt; La_&lt;1/3&gt; FeO_&lt;3-&gt; were made under high pr\in order to study the pr\dependence of charge disproportionation and magnetic ordering。我们发现在高压下，Sr_&lt;2/3&gt; La_&lt;1/3&gt; FeO_&lt;3-&gt;变成一个含有高铜的铁磁铁 ... More 这里的温度。我们对双层perovskite Sr_3Fe_2O_7和三层perovskite LaSr_3Fe_3O_<10>和在这些化合物中发现电荷分散剂。我们还在Sr_3Fe_2O_7中找到了一个物理磁性排序，在LaSr_3Fe_3O_&lt;10-&gt;中找到了一个常规的。同步加速器辐射的内体核共振散射是在CaFeO_3和Sr_&lt;2/3&gt; La_&lt;1/3&gt; FeO_&lt;3-&gt;国家的铁局部声子密度上产生的变化，其相对于电荷排序温度。在对CaFeO_3和Sr_&lt;2/3&gt; La_&lt;1/3&gt;FeO_3的核共振散射的测量中，弹性峰值在磁性相变中的强度出现了戏剧性变化。Element-selective inelastic nuclear resonance scManagement measurements from ^<161>Dy and ^<57>Fe nuclei were made on perovskite-type DyFeO_&lt;3-\。Dy和Fe状态的局部声子的密度与外壳模型计算相比较，以及模式分配是制造的。根据软X射线吸收中的磁循环失调的测量，SrFe_&lt;1-x&gt;Co_xO_3的电子和磁状态及其被共同替换识别的变化。PrNiO_3的单一晶体在高压下合成。它发现了一个跨越金属绝缘体过渡的符号，而对称性从正对称到单对称性不等。Furthermore，电荷分配在镍位点的绝缘性阶段得到确认。Triclinic perovskite PrNi0_3在高压下被合成。Bi atoms at the Asites were found to charge-disproportinate into Bi^&lt;3+&gt; and Bi^&lt;5+&gt;。我们发现，当La^&lt;3+&gt;这些离子被替换为Bions，一个金属绝缘体的过渡作为原子组成的一个功能。根据关于全氧化物类型的光发射结果的基础，我们提出，在已知的金属相位中有两种金属状态，被称为传统的保利-准磁性相位和具有胡椒粒的Curie-Weiss准磁性相位。Less（低）

・ 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