Development of electron resonance inelastic scattering and its application to orbital order analysis of perovskite manganese oxides

本研究旨在建立一种利用内壳激发的非弹性散射分析强相关电子系统中d电子轨道序的方法，并将该方法应用于具有高温超导性、巨磁电阻性等多种电子特性的mn -钙钛矿氧化物。得到如下结果：(1)通过会聚束电子衍射确定nd0.5 sr0.5 mno3的空间群为pmnm。(2)在Mn-Lshell激发下，nd0.5 sr0.5 mno3的空穴态在非弹性散射模式下表现出显著的各向异性。观察到两种各向异性，一种与CE型轨道序模型一致，另一种与CE型轨道序模型不一致。基于pmmn的空间群和非弹性散射各向异性，提出了一种新的轨道序模型。

The present research study is aimed to develop a method to analyze the orbital order of d-electrons in strongly-correlated electron systems by inelastic scattering accompanied by inner-shell excitation and to apply the method to Mn-perovskite oxides, which show a variety of electronic properties such as high-temperature superconductivity, giant magnetoresistivity, etc. The following results are obtained. (1)The space group of Nd0.5Sr0.5MnO3is determined to be Pmnmby convergent-beam electron diffraction. (2)The hole state of Nd0.5Sr0.5MnO3shows significant anisotropy in inelastic scattering patterns accompanied by Mn-Lshell excitation. Two kinds of anisotropies are observed, one of which is consistent to the CE type orbital-order model, whereas the other is inconsistent to the model. A new model of the orbital order is proposed on the basis of the space group of Pmnmand the inelastic scattering anisotropy.