Theoretical studies on the high-energy excitation spectra of multinary compounds

本研究阐明了高能光谱作为研究多元化合物电子状态的工具的能力。特别注意的是过渡金属氧化物的氧1 s共振X射线发射光谱（O 1 s RXES）的理论研究。目前的理论计算表明，O 1 s RXES为我们提供了信息的巡游价电子以及本地化的。以绝缘铜氧化物为例，观察到了由于电子从Zhang-Rice单重带跃迁到Hubbard上带（UHB）而引起的非弹性X射线散射。本研究还预测了O 1 sRXES中入射和散射X射线之间的极化相关很强，阐明了一维Y2 BaNiO 5型镍化合物的电子态。对O_（1 s）RXES和O_（1 s）X射线吸收谱（O_（1 s）XAS）的理论计算表明，Hund ...更多信息 耦合对于理解价电子态是非常重要的。对于二价镍化合物，本理论预测了一种新的激发类型。它由同时双激发在遥远的Ni离子，其中每个Ni的Ni 3d自旋状态从三重态到单线态的改变。为了强调综合分析各种高能谱的重要性，我们将研究扩展到Cu 2 p X射线光电子能谱（Cu 2 p XPS）、角分辨光电子能谱（ARPES）和Cu 1 s共振非弹性X射线散射（Cu 1 s RIXS）的计算。通过对Cu 2 p XPS谱与ARPES谱的载流子掺杂依赖性的理论计算，揭示了它们之间的密切关系。此外，我们还研究了Cu 3d轨道简并对Cu 1 s RIXS的影响，揭示了Cu 1 s RIXS中的dd激发机制。结果表明，Cu 1 s RIXS的激发选择规则与O 1 s RXES的激发选择规则在许多方面有所不同。这表明Cu 1 s RIXS和O 1 s RXES是互补的。少

The present research clarified the capability of high-energy spectroscopies as tools to investigate the electronic states of multinary compounds. Particular attention was paid to the theoretical studies on the oxygen 1s resonant x-ray emission spectroscopy (O 1s RXES) of transition-metal oxides. The present theoretical calculations showed that the O 1s RXES provides us with information on the itinerant valence electrons as well as the localized ones. In the case of insulating cuprates for instance, it observes the inelastic x-ray scattering due the electronic transition from the Zhang-Rice singlet band to the upper Hubbard band (UHB). The present research also predicted that the polarization correlation between incident and scatted x-rays is very strong in the O 1s RXES.The present research clarified the electronic state of one-dimensional Y_2BaNiO_5-type nickel compounds. The theoretical calculations on the O 1s RXES and O 1s X-ray absorption spectrum (O 1s XAS) showed that the Hund's … More coupling is very important in understanding the valence electron states. For divalent Ni compounds, the present theory predicted a new type of excitation. It consists of simultaneous double excitations at distant Ni ions, where the Ni 3d spin state of each Ni is changed from triplet to singlet. We also succeeded in observing the excitation in NiO.In order to emphasize the importance of comprehensive analysis of various high-energy spectra, we extended the study to the calculations of Cu 2p x-ray photoemission spectroscopy (Cu 2p XPS), angle-resolved photoemission (ARPES) and Cu 1s resonant inelastic x-ray scattering (Cu 1s RIXS). We also showed a close relationship between the Cu 2p XPS and ARPES through the theoretical calculations on the carrier doping dependence of those spectra Moreover, we studied the effects of Cu 3d orbital degeneracy on the Cu 1s RIXS to show the dd excitation mechanism in the Cu 1s RIXS. The result showed that the excitation selection rules of the Cu 1s RIXS differ from those of the O 1s RXES in many respects. It indicates that the Cu 1s RIXS and O 1s RXES are complementary to each other. Less